What Do the Sciatic Nerve and Leavened Food on Passover Have to Do with One Another? The Historical Origins of These Eating Prohibitions and Their Implications for Their Halakhic Definition

With God's help

Sinai – 5769 (2009)

Michael Abraham

Rabbinic instructor at the Institute for Advanced Torah Studies, Bar-Ilan University

052-3320543

mikyab@gmail.com

Introduction

The prohibition against eating leavened food appears in the Torah in several places. In all of them, leaven and leavened food are mentioned interchangeably, and ostensibly this implies that leaven and leavened food are synonymous terms for the very same prohibition.

For example, Exodus 12:15:

For seven days you shall eat unleavened bread, but on the first day you shall remove sourdough from your houses, for whoever eats leaven, that soul shall be cut off from Israel, from the first day until the seventh day.

Likewise, ibid. 12:19:

For seven days no leaven shall be found in your houses, for whoever eats anything leavened, that soul shall be cut off from the community of Israel, whether a stranger or a native of the land.

In both of these sources, the obligation of removal applies to leaven, whereas the prohibition of eating applies to leavened food.

And in another source we find (ibid. 13:7):

Unleavened bread shall be eaten throughout the seven days, and no leaven shall be seen with you, nor shall any sourdough be seen with you, in all your territory.

Here too, both leaven and leavened food are presented as subject to the prohibition of being seen.

But as is well known, leaven is not fit for eating, not even for a dog.[1] For we find in Tosefta Beitzah, ch. 1 halakhah 7 (see also Hagahot Maimoniyot on ch. 1 of Hilkhot Hametz, subsec. 2):

What is “se'or”? Something that causes others to become leavened. What is “hametz”? Something that itself became leavened through another substance. From when is it called “se'or”? From the point that it becomes unfit even for a dog’s consumption.

Now, foods that are unfit for human consumption (even if they are fit for a dog) are not prohibited under ordinary eating prohibitions (see Maimonides, Hilkhot Ma'akhalot Asurot, ch. 14 halakhah 11). Moreover, later authorities wrote that eating something unfit for consumption is less severe than eating in an atypical manner of enjoyment, for which one is also exempt, because here not only is there no act of eating, but the forbidden item is not even an object of prohibition (see Havot Da'at sec. 103 and elsewhere).[2]

If so, it is now unclear why the Torah prohibits even leaven, although it is unfit for eating. How can there be a prohibition of eating something that is unfit for eating? Several later authorities noted this (see Ahiezer Yoreh De'ah sec. 11 subsec. 3, and likewise in Minhat Hinukh commandment 19, citing the Pri Megadim, and in the notes to the Machon Yerushalayim edition there), and some attributed it to a special textual innovation, that Scripture explicitly prohibited even leaven, but this still requires explanation. Moreover, even regarding leavened food, one who eats leavened food that is unfit for consumption is exempt.[3] If so, how does the law of leaven differ from ordinary leavened food that is unfit for consumption?[4]

In this article we shall propose a possible explanation for this, primarily within Maimonides' approach, and we shall point to parallels between the prohibition of leavened food and the prohibition of the sciatic nerve. In our discussion we shall distinguish between three types of eating prohibitions, and we shall examine several halakhic implications of this distinction.

The passage in Beitzah: leaven and leavened food

The opening mishnah of Beitzah presents the dispute between Beit Hillel and Beit Shammai:

Beit Shammai say: sourdough is in the amount of an olive-bulk, and leaven is in the amount of a date; and Beit Hillel say: both this and that are in the amount of an olive-bulk.

On its face, the dispute concerns the prohibition of eating leavened food, and the question is whether the measure of leaven for this purpose is similar to, or different from, the measure for ordinary leavened food.

Now in the Gemara, 7b, we find:

What is Beit Shammai’s reason? If so, the Merciful One should have written only “leaven,” and there would be no need for “sourdough,” and I would have said: if leaven, whose leavening action is not as strong, is prohibited in the amount of an olive-bulk, then sourdough, whose leavening action is stronger, all the more so. Why, then, did the Merciful One write “sourdough”? To tell you that the measure of this one is not like the measure of that one.

Beit Shammai hold that if the verse had written only leavened food and not leaven, we would have derived leaven by an a fortiori argument, since its fermentation is stronger than that of ordinary leavened food. From this Beit Shammai conclude that the appearance of the word 'leaven' must come to teach that the measure for one is not the same as the measure for the other. Why specifically is leavened food measured by the size of a large date, while leaven is measured by an olive-bulk? Presumably because, according to Beit Shammai's logic in their a fortiori argument, leaven is the more severe prohibition, since its fermentation is stronger, and therefore a smaller amount suffices for liability for eating it.

What do Beit Hillel answer to this? The Gemara states:

And Beit Hillel say: both are necessary. For if the Merciful One had written only “sourdough,” I would have said it is because its leavening action is stronger; but leaven, whose leavening action is not as strong—I would say no, so it is necessary. And if the Merciful One had written only “leaven,” it is because it is fit for eating; but sourdough, which is not fit for eating—I would say no, so it is necessary.

Beit Hillel disagree with Beit Shammai and argue that there is a refutation of their a fortiori argument from leavened food to leaven, because leaven is not fit for eating. Therefore, had the Torah not written the prohibition of leaven, I would have thought that only leavened food is prohibited for eating and not leaven, because leaven is unfit for eating, like the other Torah prohibitions that do not apply when consumed in an abnormal way or when the item is unfit for consumption.

It seems that Beit Shammai are not troubled by the fact that leaven is unfit for eating. Let us note that even according to Beit Hillel, as practical Jewish law, leaven is prohibited for eating because the Torah prohibited it, but in their view this is the result of the fact that the verse explicitly prohibited it. Without the verse, we would have thought that leavened food is like all the other prohibitions in the Torah, and that it is prohibited only when it is fit for eating. But according to Beit Shammai, this would be true even without the verse, since if the verse had not written leaven but only leavened food, Beit Shammai would have learned by an a fortiori argument that leaven too is prohibited for eating. Why do they not take into account that it is unfit for eating, as with all the eating prohibitions in the Torah? Even according to Beit Hillel this requires discussion. True, they learn it from the verse, but why is this so in fact? How does the prohibition against eating leavened food differ from the other eating prohibitions in the Torah? And furthermore, how does leaven differ from other leavened matter that is unfit for eating?

Afterward, the Gemara rejects the possibility that the dispute concerns eating prohibitions, and instead establishes it as concerning the duty of removal:

And do Beit Shammai not accept Rabbi Zeira’s view? For Rabbi Zeira said: Scripture began with “sourdough” and concluded with “leaven,” to tell you: this is sourdough, this is leaven. Regarding eating, everyone agrees; where they disagree is regarding removal. Beit Shammai hold: we do not derive removal from eating; and Beit Hillel hold: we do derive removal from eating. It was also stated likewise: Rabbi Yosei bar Ḥanina said, the dispute is regarding removal, but regarding eating, everyone agrees that both this and that are in the amount of an olive-bulk. It was also taught likewise: “No leaven shall be seen with you” and “no sourdough shall be seen with you”—this is the dispute between Beit Shammai and Beit Hillel, for Beit Shammai say: sourdough is in the amount of an olive-bulk and leaven is in the amount of a date, while Beit Hillel say: both this and that are in the amount of an olive-bulk.[5]

In conclusion, the dispute between Beit Shammai and Beit Hillel concerns the measure relevant to the obligation of removal of leavened food, whereas regarding eating there is no dispute, and according to all opinions the measure for both leaven and leavened food is an olive-bulk.

Again, one should note that Beit Shammai's view was not rejected because it is unreasonable to ignore the fact that leaven is unfit for eating. This point did not trouble the Gemara. What rejected that understanding of the dispute was only Rabbi Zeira's exposition. This sharpens the fact that the Gemara's initial assumption still requires explanation even according to the conclusion: why is the Gemara not troubled by the apparent irrelevance of fitness for eating with respect to the prohibition of eating leavened food?

Maimonides' halakhic ruling

Now Maimonides, in ch. 1 halakhah 2 of Hilkhot Hametz, brings the Gemara's conclusion. In order to see the context, let us cite his first two halakhot in Hilkhot Hametz u-Matzah:

1. Anyone who eats an olive-bulk of leaven on Passover, from the beginning of the night of the fifteenth until the end of the twenty-first day of Nisan, intentionally, is liable to karet, as it says: “For whoever eats leaven… shall be cut off.” If unintentionally, he is liable to bring a fixed sin-offering. This applies both to one who eats it and to one who melts it and drinks it.

2. Leaven on Passover is prohibited for benefit, as it says: “Leaven shall not be eaten”—there shall be no permission to derive benefit from it through eating. One who leaves leaven in his possession on Passover, even if he does not eat it, violates two prohibitions, as it says: “No sourdough shall be seen with you in all your territory,” and it says: “No sourdough shall be found in your houses.” The prohibition of leaven and the prohibition of sourdough used for leavening are one and the same.

From the end of his remarks in halakhah 2, we see that Maimonides views the prohibition of leavened food and the prohibition of leaven as one and the same prohibition. It appears that this applies both to eating, where this is agreed, and to removal, since the law follows Beit Hillel.

His wording too seems to indicate, as we noted above, that here there is a scriptural decree that it is forbidden to eat leaven even though it is unfit for eating. From his words it also appears that he is trying to offer an explanation for this: leaven is the substance with which other doughs are leavened, and therefore it certainly falls under the category of leavened food. That is, the difference between ordinary leavened food that is unfit for eating and leaven is that ordinary leavened food that is unfit for eating no longer bears the designation 'leavened food', whereas leaven, by means of which other doughs are leavened, still bears the designation 'leavened food' even though it is unfit for eating. What causes leavening certainly itself bears the name 'leavened food'.

There seems to be some similarity between this reasoning and what we find in ch. 9 halakhah 14 of Hilkhot Shabbat, where Maimonides disputes with the Ra'avad regarding the preparation of dye in relation to the labor of dyeing:

One who produces a dye bath is a derivative of the labor of dyeing and is liable. How so? For example, if he put copper sulfate into gall-nut water so that everything became black, or if he put indigo into saffron water so that everything became green, and so too anything similar. And what is the measure? Enough to dye a thread four handbreadths long.

/Raavad's gloss/ How does dyeing work? For example, if one put copper sulfate into gall-nut water and the water became colored. Raavad said: this is difficult for me—regarding cooking dyes, from which we derive the labor of cooking (Sabbath 74), why not derive liability also משום dyeing the water?And I would not have thought one is liable for dyeing unless he dyed something for which the dyeing process is thereby completed; but dyeing water, when it is not for the water’s own sake, no.And soaking ink and dyes falls under kneading, not because of coloring the water, just like soaking vetches, and similar to water and flour or water and earth.

Maimonides holds that the preparation of dye is included in the labor of dyeing, since the dye is the thing with which other items are dyed.[6] This is reasoning similar to what we see in his words here: the dye is the thing by means of which other things are dyed, and therefore its preparation certainly falls under the category of dyeing. So too, leaven bears the designation 'leavened food', since it is the thing with which other doughs are leavened and turned into leavened food.[7]

However, the matter still requires clarification. Even if this reasoning shows us that leaven bears the designation 'leavened food', this still does not solve the basic problem of how such leaven can be prohibited for eating if it is unfit for eating. Why is it enough for us to say that leaven bears the designation 'leavened food' in order to explain the rule that it is prohibited for eating? After all, even if it bears the name leavened food, it would seem that it should be permitted, like the other eating prohibitions in the Torah. This is especially true according to Beit Shammai, who knew how to prohibit leaven even without the Torah's special innovation.

In order to understand the matter, let us begin with a general discussion of eating prohibitions in general, and afterward return to the prohibition of leavened food.

The relation between a prohibition of eating and a prohibition of benefit

The dispute of the amoraim in Pesahim 21b regarding the relation between eating prohibitions and prohibitions of benefit in the Torah is well known:

Hezekiah said: From where do we know that leaven on Passover is prohibited for benefit? As it is said, “Leaven shall not be eaten”—there shall be no permission to derive benefit from it through eating. The reason is that the Merciful One wrote “shall not be eaten”; had He not written “shall not be eaten,” I would have said that it implies only a prohibition of eating, but not a prohibition of benefit. And this disagrees with Rabbi Abbahu, for Rabbi Abbahu said: Everywhere that it says “shall not be eaten,” “you shall not eat,” or “you shall not eat,” it implies both a prohibition of eating and a prohibition of benefit, unless Scripture specifies otherwise, as it specified with regard to carcass-meat. For it was taught: “You shall not eat any carcass; to the stranger within your gates you may give it, that he may eat it, or you may sell it to a foreigner”…

Rabbi Abbahu holds that if the Torah states a prohibition in the language of eating, such as 'you shall not eat' and the like, this includes a prohibition of benefit as well, unless there is an explicit indication in the verse, as in the case of carrion, where the Torah permitted selling it to a gentile or giving it to the resident alien, that it is permitted for benefit. By contrast, Hezekiah does not accept this, and in his view an additional source is needed to teach that the item is prohibited for benefit as well. Regarding leavened food, he adduces such a source from the fact that the verse used the passive language 'it shall not be eaten' rather than 'you shall not eat' or something similar. Rashi explains that 'it shall not be eaten' teaches that leavened food is prohibited for benefit, and the apparent meaning of his words is that the passive formulation implies that the prohibition is that the leavened food be eaten by someone, such as a gentile, even though a gentile is certainly not subject to the prohibition of leavened food. It therefore seems that the reason must be that the Jew sold him the leavened food and benefited from its price. In other words, the prohibition is against benefit from leavened food, not only against eating it. According to Rabbi Abbahu, it is quite clear that the prohibition of benefit regarding leavened food does not require any special derivation from the passive formulation of the verse, and on his view, even if the prohibition of eating leavened food had been written in the ordinary active form, such as 'you shall not eat', we would still know that leavened food is prohibited for benefit.

Maimonides' approach to eating prohibitions

Maimonides, in ch. 8 of Hilkhot Ma'akhalot Asurot, halakhah 15, rules in accordance with Rabbi Abbahu:

Everywhere the Torah says “you shall not eat,” “you shall not eat,” “they shall not eat,” or “it shall not be eaten,” it implies both a prohibition of eating and a prohibition of benefit, unless Scripture specifies otherwise, as it specified with regard to carcass-meat, as it says, “to the stranger within your gates you may give it, that he may eat it,” and with regard to forbidden fat, where it says, “it may be used for any labor”; or unless it is explained in the Oral Torah that it is permitted for benefit, such as creeping creatures, swarming creatures, blood, a limb from a living animal, and the sciatic nerve—all of these are permitted for benefit by received tradition even though they are prohibited for eating.

In his Commentary on the Mishnah to tractate Keritot, ch. 3 mishnah 4, Maimonides points to an important implication of Rabbi Abbahu's conception, which he calls there a 'wondrous point':

There is a remarkable point in what we have said here, and I will call attention to it, because it is a key to other matters in addition to the precision it yields in analysis. It is well known that meat cooked with milk is prohibited for benefit, while forbidden fat, for example, is permitted for benefit. So if one cooked meat with forbidden fat, why should the prohibition of meat with milk not take effect upon the preexisting prohibition of forbidden fat? The same would apply to carcass-meat, since it is an added prohibition, as we said here regarding consecrated forbidden fat, where we held one liable for misuse of sacred property because a prohibition of benefit was added. The answer is that meat cooked with milk is prohibited for benefit only because Scripture prohibited its consumption, according to the rule we explained: whatever is prohibited for eating is also prohibited for benefit unless Scripture specifies otherwise. There is not one verse prohibiting its consumption and another prohibiting benefit; rather, both together constitute the prohibition of meat with milk. Since we have said that one prohibition does not take effect where another prohibition already exists, and therefore the prohibition of meat with milk does not take effect upon the prohibition of carcass-meat, it follows that it is not prohibited for benefit at all, but remains permitted for benefit, and one who eats it is lashed only for carcass-meat. The prohibition of meat with milk thus falls away entirely, since it never took effect. But there would have been room to object and compare it to consecrated forbidden fat only if we had said that it was prohibited for benefit, as we said regarding sacred offerings, and that one who ate it was not liable for meat with milk; then there would have been room for the objection. But that is not so. Rather, we say that this meat cooked with milk is not prohibited for benefit. Indeed, you see that the Mishnah states that the meat of an impure animal may be cooked and is permitted for benefit, and this has already been explained in its proper place. Understand this matter well, for it is a place where one can easily err, and on its basis you should judge every similar case.

Maimonides explains that meat cooked in milk is prohibited for benefit as part of its eating prohibition, in accordance with Rabbi Abbahu, and therefore the prohibition of meat cooked in milk does not take effect on the preexisting prohibition of forbidden fat, even though meat cooked in milk also carries a prohibition of benefit, which should seemingly take effect under the rule of an added prohibition. Why is a separate verse required to prohibit meat cooked in milk for benefit, besides the verse that prohibits it for eating? Here the answer is that the eating prohibition of meat cooked in milk is not stated in the Torah in the language of eating, but is derived by exegesis from the repeated verse 'Do not cook a kid in its mother's milk', that is, from language of cooking. But once the Sages interpreted the third verse as coming to prohibit benefit, we learn that the prohibition of benefit is part of the eating prohibition.

Another implication of this point is that the prohibition of benefit regarding meat cooked in milk is not counted separately in the enumeration of the commandments, but is included within the prohibition of eating it. Maimonides explains this in Sefer HaMitzvot, negative commandment 187, and in the course of his remarks there he adds a further explanation of Rabbi Abbahu's view. The matter is also copied at great length in the Sefer HaChinukh, commandment 113:

Commandment 187 is the prohibition against eating meat cooked with milk, as He likewise said a second time, “You shall not cook a kid in its mother’s milk.” This refers to the prohibition of eating. In tractate Hullin they said: for meat cooked with milk one is lashed for its cooking and lashed for its eating. And in tractate Makkot they said: one who cooks the sciatic nerve in milk on a Jewish holiday and eats it receives five sets of lashes—one for eating the sciatic nerve, one for cooking the sciatic nerve, one for cooking meat with milk, one for eating meat with milk, and one for kindling. And there they say: remove kindling and insert wood of sacred property, whose prohibition is derived from here: “And their asherim you shall burn with fire; you shall not do so to the Lord your God.” And in tractate Hullin they said: for this reason the Merciful One expressed the eating prohibition in the language of cooking, so that just as one is lashed for the cooking, so too one is lashed for the eating. And in the second chapter of Pesahim they said regarding meat with milk: for this reason the Merciful One did not write “eating” explicitly with regard to it—to teach that one is lashed for it even when it is not consumed in the ordinary manner of benefit. Remember this.

Here it is proper for me to allude to a great principle that I have not previously mentioned. The statement “You shall not cook a kid in its mother’s milk” is repeated in the Torah three times. The masters of interpretation said that each of these prohibitions serves a distinct purpose: one for the prohibition of eating, one for the prohibition of benefit, and one for the prohibition of cooking. If someone should ask: why did you count the prohibition of eating it and the prohibition of cooking it as two commandments, but not count the prohibition of deriving benefit from it as a third commandment?—let the questioner know that the prohibition of benefit should not be counted as an independent commandment, because it and the prohibition of eating are one matter, for eating is one form of benefit. When Scripture says of something that it may not be eaten, this is one expression of the broader category of benefit; the intention is that one may not derive benefit from it, whether by eating or otherwise. This is what the Sages said: everywhere that it says “you shall not eat,” “you shall not eat,” or “it shall not be eaten,” it implies both a prohibition of eating and a prohibition of benefit, unless Scripture specifies otherwise, as it did with carcass-meat, where it explained the permission to derive use from it, saying: “to the stranger within your gates you may give it, that he may eat it,” etc. According to this principle, the prohibition of eating and the prohibition of benefit should not be counted as two commandments. If we were to count them as two commandments in the case of meat with milk, then similarly with leaven, orlah, and vineyard mixtures, in each of these four cases the prohibition of benefit should likewise be counted as an independent commandment. Since in those cases he did not count anything beyond the prohibition stated regarding their eating, and the prohibition of benefit is included within that as we have explained, the same must apply to meat with milk. There remains only one question: since the prohibition of benefit follows from the prohibition of eating, as the Sages explained, why did Scripture need a third prohibition in the case of meat with milk in order to make benefit from it forbidden, as we have explained? The answer is that this was necessary because with meat and milk Scripture did not say “you shall not eat of it,” from which both the eating and the benefit prohibitions would have been derived; therefore another prohibition was needed to prohibit benefit. We have already mentioned the reason why the Merciful One did not write “eating” with regard to meat with milk: whenever eating is stated, one is liable only if one derives enjoyment from the eating; but if one merely opens his mouth and swallows one of the forbidden substances, or eats it while it is so hot that it burns his throat and causes him pain while swallowing, and the like, he is exempt—except for meat with milk, for which he is liable upon eating it even if he derives no enjoyment, as they said, and similarly with a vineyard mixture, as will be explained later. Understand and remember all these principles. The laws of this commandment have been explained in the eighth chapter of tractate Hullin.

Maimonides here explains the basis of his reading of Rabbi Abbahu. When the Torah prohibits something in eating, we view eating merely as an example used to prohibit deriving benefit from it. Just as when the Torah speaks of one man's ox goring another's, it does not mean only oxen but all damaging property, the ox is merely a common example the Torah uses to illustrate a general principle. So too, when the Torah prohibits something in the language of eating, we see this only as an example of a common form of benefit. In truth, the Torah's intent is to prohibit deriving benefit from the thing, including by eating it.

At the end of his remarks there, Maimonides adds an explanation, based on the passage in Pesahim 25a, of why the Torah did not formulate the prohibition of meat cooked in milk in the language of eating, in which case a single verse could have taught us that it is prohibited both for eating and for benefit. Why were two verses and expositions that depart from the simple sense needed to teach us something that could have been learned from one verse? Maimonides explains that the prohibition of meat cooked in milk is an exceptional eating prohibition, because it is not a prohibition of enjoyment through eating, but a prohibition of the act of eating as such. The practical consequence is that, with meat cooked in milk, there is a prohibition to eat even when one derives no enjoyment, for example when it is scalding hot.

A further conclusion emerges from here, one that Maimonides takes for granted. When a prohibition is written in the ordinary language of eating, the prohibition is not against performing an act of eating, but against deriving enjoyment in the manner of eating, and since this is only an example, the conclusion is that deriving benefit in any other way is forbidden as well. But when a prohibition is written in some other formulation, the prohibition is against performing an act of eating upon the forbidden object, and not necessarily against deriving enjoyment from it. Therefore, even an act of eating from which no enjoyment is derived will be prohibited in a prohibition of this type.

This distinction gives us a clue to the nature of the prohibition of eating leavened food. There too we saw that this is a prohibition under which one may not eat even leaven that is unfit for eating. We now return to our subject and spell this out more fully.

The foundation of Maimonides' view regarding the prohibition of leavened food

We saw above that Maimonides, in ch. 1 halakhah 2, brings Hezekiah's derivation from the passive form 'it shall not be eaten' as the source for the prohibition of benefit regarding leavened food. Later authorities found it difficult why he needs Hezekiah's derivation concerning the prohibition of benefit from leavened food, even though he rules in accordance with Rabbi Abbahu. For example, the Kesef Mishneh ad loc. writes:

And our master, although he rules like Rabbi Yehuda, wrote regarding Passover in the formulation of Hezekiah, even though he holds like Rabbi Abbahu, as is explicitly explained in chapter 8 of the laws of Forbidden Foods, and it also appears in chapter 2 of the laws of Slaughter that he holds that way, for he wrote that slaughtering non-sacred animals in the Temple courtyard is only prohibited by received tradition—and that is like Rabbi Abbahu, as stated in the chapter Kol Sha'ah, whereas according to Hezekiah, non-sacred animals in the courtyard are a Torah prohibition. Yet in this chapter he wrote that leaven on the 14th from midday onward is prohibited for benefit, like Rabbi Yehuda, and there the verse does not say “it shall not be eaten” but “you shall not eat,” and nevertheless it is prohibited for benefit, in accordance with Rabbi Abbahu. Even though Tosafot wrote on page 28 that according to Hezekiah too, before its proper time it is prohibited for benefit because once one of these verses implies a prohibition of benefit, we do not distinguish among them—still, from what he wrote in chapter 8 of the laws of Forbidden Foods and chapter 2 of the laws of Slaughter, it is explicit that he holds like Rabbi Abbahu. Even so, regarding the prohibition of benefit on Passover, since there is a particularly explicit verse to which everyone agrees, he adopted that formulation. Something similar was written by the Ran on the Rif.

The Kesef Mishneh explains that Maimonides cited Hezekiah's derivation because it seemed more directly suited to the verse, although in truth he did not need it. This is of course forced, especially since that very point is the subject of the amoraic dispute in the passage cited above, and Maimonides would seemingly be misleading us here on a very fundamental matter concerning all eating prohibitions. We shall therefore suggest a different explanation of Maimonides' words, and we shall see that it fits his approach elsewhere as well.

Maimonides apparently holds that the prohibition of eating leavened food is a prohibition different in kind from the other eating prohibitions. It is a prohibition of the act of eating, not a prohibition of deriving benefit through eating. This prohibition resembles what we saw above in his words regarding meat cooked in milk. Therefore one cannot derive from the prohibition of eating leavened food that leavened food is also prohibited for benefit, just as we saw in his discussion of meat cooked in milk, and that is why Maimonides requires an additional source here for the fact that leavened food is also prohibited for benefit.

What is Maimonides' source for this conception? At first glance, the passage in Pesahim seems not to assume this, since it presents the dispute between Rabbi Abbahu and Hezekiah regarding leavened food itself.

It seems that Maimonides' source is the passage in Beitzah cited above. According to Beit Hillel, whose view is the law, this definition is learned from the very fact that there is a prohibition of eating leaven, even though it is unfit for eating. Maimonides understands that the reason for this is that the prohibition of eating leavened food is not a prohibition of benefit from eating leavened food, but a prohibition of the act of eating performed on something called 'leavened food', even if no enjoyment is derived from it.

As we saw, according to Beit Shammai the matter goes even further. In their view, this conception of the prohibition of eating leavened food, as a prohibition of action and not a prohibition of benefit by means of eating, would have been clear even without the verse about leaven, that is, even had the Torah not written explicitly that leaven too is prohibited. How can Beit Shammai assume such a thing?

It seems that the basis of the matter lies in simple reasoning. Ordinary eating prohibitions express the fact that the thing prohibited is repugnant in a spiritual sense. The Torah warns us to distance ourselves from deriving benefit from repugnant things, and therefore prohibits them in the form of eating-benefit, and by implication in every other form of benefit as well. But leavened food is not repugnant in itself, for before Passover and after Passover it is entirely permitted for us to eat it. So why is it prohibited? Because the Torah wants us thereby to remember the Exodus from Egypt. Just as our ancestors did not eat leavened food, so too we are meant not to perform an act of eating upon leavened food. There is no problem in benefit from leavened food as such; what is prohibited is the act of eating leavened food, as a reenactment of what took place at the Exodus from Egypt. It is possible that for this reason Beit Shammai understood that the basis of the prohibition of eating leavened food is not a prohibition of benefit through eating, but a prohibition of the act of eating. Below we shall see a parallel in the prohibition of the sciatic nerve.[8]

We can now understand the course of Maimonides' remarks in the first two halakhot of Hilkhot Hametz u-Matzah, cited above. First, Maimonides separates the eating prohibition and the prohibition of benefit into two separate halakhot, because here they really are two different prohibitions. The first is a prohibition of the act of eating, not necessarily of enjoyment through eating, and the second is a prohibition of deriving benefit from leavened food. Second, consistent with his view, Maimonides needs Hezekiah's source here in order to prove that leavened food is prohibited for benefit, and he does not derive this from the eating prohibition. Third, Maimonides concludes halakhah 2 by stating that leaven too is prohibited for eating because it leavens other doughs, and by this he explains why leaven too is prohibited for eating despite being unfit for eating. Above we had difficulty with this explanation, for at most it proves that leaven is called 'leavened food', but why should it be prohibited for eating if it is unfit for eating? We can now understand that the fact that it is unfit for eating does not exempt in a prohibition of this kind, as we saw in Maimonides with respect to meat cooked in milk. The only question is whether leaven bears the designation 'leavened food' or not, such that eating it counts as eating something called 'leavened food'. To that Maimonides brings his reasoning, similar to the labor of dyeing: if leaven ferments other doughs, then it is certainly a more intense instance of leavened food than ordinary leavened food. Moreover, the fact that leaven is unfit for eating is precisely because of its fermentation, not because it has become disgusting, and therefore it is clear that this does not remove the designation 'leavened food' from it. This aspect shows that leaven is more fully leavened food, not less. This is precisely Beit Shammai's reasoning, for they learned by an a fortiori argument that leaven is prohibited from the prohibition of leavened food, because leaven is more fermented, and they were not troubled by the fact that it is unfit for eating. In their view, the fact that it is more sour is a reason for greater prohibition, irrespective of its being unfit for eating. From this Maimonides learned that leaven certainly bears the designation 'leavened food', and accordingly there is a prohibition against eating it, since eating it is an act of eating performed on something called 'leavened food', and that is the definition of the prohibition against eating leavened food.

The question now arises why we do not likewise prohibit eating ordinary leavened food that is unfit for eating. The explanation is that leavened food which is unfit for eating is no longer food, and therefore it no longer bears the designation 'leavened food'. One who eats it is exempt because there is no 'leavened food' here, and therefore there is no act of eating leavened food. Only leaven, whose unfitness for eating is precisely because of its extreme fermentation, certainly does not lose its designation as 'leavened food'.[9] I later saw that the Avnei Nezer, Orah Hayyim sec. 349, especially subsec. 18, already made this point. However, the Sha'agat Aryeh, sec. 75, sought to prove that eating in an atypical manner is more severe than eating something unfit for consumption, from the fact that meat cooked in milk and mixed plantings of the vineyard are prohibited even when consumed not in the normal manner of enjoyment, whereas if they are unfit for eating one is exempt even there. In truth, this means that when something is unfit for eating it no longer bears the status of food, and therefore one is exempt, just as we are arguing here.

Let us explain this a bit more. In the case of the other ordinary eating prohibitions, when the prohibited food becomes repugnant the exemption is both because there is no enjoyment from the prohibition and because it no longer bears the designation of that prohibition. It is no longer 'pork', because it is no longer food. But with leavened food, enjoyment is irrelevant to the prohibition, and therefore the exemption exists only because there is no leavened food here. The practical difference concerns leaven. According to Maimonides' reasoning, leaven still bears the designation 'leavened food' even though one derives no enjoyment from eating it. Therefore, despite the absence of enjoyment, there is no exemption from the prohibition.

This is the course of Maimonides' words in halakhot 1-2. He separates the prohibition of eating from the prohibition of benefit, and brings a separate source for the prohibition of benefit. From there he moves immediately to show that the prohibition of leaven and the prohibition of leavened food are one and the same prohibition, because in both cases what is eaten bears the designation 'leavened food', by virtue of the reasoning that leaven ferments other doughs and is therefore certainly leavened food. That is why the identification of leaven with leavened food appears precisely in this halakhah.

The prohibition of eating the sciatic nerve

There is another eating prohibition that was instituted as a memorial to a historical event, namely the sciatic nerve. The prohibition of the nerve is a remembrance of Jacob's struggle with the angel, as stated explicitly in the verse (Genesis 32:33):

ThereforeTherefore the children of Israel do not eat the sciatic nerve, which is upon the socket of the thigh, to this day, because he touched the socket of Jacob’s thigh at the sciatic nerve.

The verse itself states that the reason for the prohibition is a remembrance of the historical event of Jacob's struggle with the angel.

Another point of similarity between the prohibition of the sciatic nerve and the prohibition of leavened food is that the sciatic nerve too is unfit for eating. Indeed, the baraita in Pesahim 22a, immediately after the dispute between Rabbi Abbahu and Hezekiah, presents a tannaitic dispute whether the nerve imparts flavor or whether it is like wood, that is, whether it has no flavor and is entirely unfit for eating. The practical consequence concerns the prohibition of benefit from the nerve. The Gemara's point of departure is an objection to Rabbi Abbahu's view:

Rabbi Yitzhak Nappaḥa raised an objection: But what about the sciatic nerve, concerning which the Merciful One said, “Therefore the children of Israel shall not eat the sciatic nerve,” and we learned: a person may send a thigh to a gentile with the sciatic nerve inside it, because its location is recognizable. Rabbi Abbahu holds that when carcass-meat was permitted for benefit, it—and its fat and its sciatic nerve—were permitted as well. This works well according to the one who says that sinews impart flavor; but according to the one who says that sinews do not impart flavor, what can be said? Whom have you heard say that sinews do not impart flavor? Rabbi Shimon, as it was taught: one who eats from the sciatic nerve of an impure animal—Rabbi Yehuda obligates him twice, and Rabbi Shimon exempts him. Rabbi Shimon likewise holds that it is prohibited for benefit, as it was taught: the sciatic nerve is permitted for benefit—these are the words of Rabbi Yehuda; Rabbi Shimon prohibits it.

From the baraita we see that according to Rabbi Judah the nerve does impart flavor, whereas according to Rabbi Shimon it does not, and therefore according to Rabbi Judah the nerve is permitted for benefit while according to Rabbi Shimon it is prohibited. Why, according to Rabbi Judah, is the nerve permitted for benefit? Hezekiah explains that a prohibition of eating does not necessarily entail a prohibition of benefit. Rabbi Abbahu, by contrast, explains that when carrion was permitted, its fat and its sciatic nerve were permitted with it. According to Rabbi Shimon, the nerve is prohibited for benefit. Why? According to Rabbi Abbahu, because every eating prohibition includes a prohibition of benefit. But what would Hezekiah say? Tosafot, s.v. 'Ve-Rabbi Shimon', loc. cit., explain in their first answer that since the nerve is unfit for eating, it stands to reason that it should be prohibited for benefit.

Already here one may ask: if indeed according to Rabbi Shimon the sciatic nerve is unfit for eating, why does the Torah prohibit it for eating? Seemingly it should have prohibited only benefit from it, especially according to Tosafot's reasoning just cited. According to our approach above, here too the prohibition is one on the act of eating, not on benefit from eating, exactly as we saw regarding leavened food. The reason is that here too we are dealing with historical reenactment and not with distancing oneself from repugnant foods. We therefore learn that the nerve too is unfit for eating like leaven, and it too was prohibited as a memorial to a historical event, and therefore here too the definition is a prohibition of the act of eating and not a prohibition of benefit through eating. Let us now see an interesting implication of this conclusion.

According to most decisors, the practical law is that nerves do not impart flavor. Maimonides, Hilkhot Ma'akhalot Asurot ch. 15 halakhah 17, and likewise the Shulchan Arukh, Yoreh De'ah 65:9, writes:

All other prohibitions in the Torah, such as the meat of creeping and swarming creatures, forbidden fat, blood, and the like, have a measure of one part in sixty. How so? If an olive-bulk of kidney fat fell into sixty olive-bulks of tail fat, everything is permitted; if it fell into less than sixty, everything is prohibited. Likewise, if a barley-grain’s worth of forbidden fat fell in, there must be about sixty barley-grains there, and so too with other prohibitions. Likewise, if the fat of the sciatic nerve fell into a pot of meat, we assess it against sixty, but the fat of the nerve itself is not counted as part of the sixty. Even though the fat of the sciatic nerve is prohibited only by rabbinic law, as we explained, since the sciatic nerve is a distinct entity, they treated it stringently like Torah prohibitions. But the nerve itself is not measured and does not prohibit, because sinews do not impart flavor.

Maimonides rules that the nerve does not impart flavor, and so too in ch. 16 of Hilkhot Ma'akhalot Asurot, halakhah 6, and therefore it is not counted for purposes of nullification. See the dispute about this in Hullin 99b.

If so, Maimonides would seem to rule like Rabbi Shimon, and therefore as practical Jewish law the nerve should be prohibited for benefit. Yet in ch. 8 of Hilkhot Ma'akhalot Asurot, halakhah 14, which is precisely the halakhah immediately preceding the one cited above where Maimonides rules like Rabbi Abbahu regarding the relation between prohibitions of benefit and eating prohibitions in general, Maimonides writes as follows:

The sciatic nerve is permitted for benefit; therefore a person may send a thigh containing the sciatic nerve to a gentile, and may give him the whole thigh intact in the presence of Jews, and we are not concerned that a Jew may eat from it before the nerve is removed, since its location is recognizable. Therefore, if the thigh had been cut up, one may not give it to a gentile in the presence of Jews until the nerve has been removed, lest a Jew eat from it.

Immediately afterward, in halakhah 15, he moves on to his general principle that whatever is prohibited for eating is also prohibited for benefit, the principle cited above.

Now in the glosses of the Ramakh, printed in the Frankel edition on halakhah 15 in Maimonides, where the sciatic nerve is also mentioned, he asks against Maimonides, and the same objection is raised by the Rosh, Hullin ch. 7 sec. 17:

Such as creeping creatures, swarming creatures, blood, a limb from a living animal, and the sciatic nerve—all of these are permitted for benefit by received tradition. This is puzzling, for I do not know why he wrote that the sciatic nerve is permitted for benefit by tradition; does he not rule shortly afterward in accordance with Rabbi Abbahu? According to Rabbi Abbahu, the sciatic nerve is prohibited for benefit. So it appears in the chapter Kol Sha'ah (22a), and this requires further analysis.

As we saw above, according to the conclusion of the Gemara in Pesahim, Rabbi Abbahu prohibits the sciatic nerve for benefit and only Hezekiah permits it. If so, Maimonides here would apparently be departing from his ruling in accordance with Rabbi Abbahu and adopting Hezekiah's view. Moreover, Maimonides rules like Rabbi Shimon that the nerve imparts no flavor, and we saw that according to Rabbi Abbahu, for Rabbi Shimon the nerve is prohibited for benefit. So how can Maimonides rule that the nerve is permitted?

According to our approach, however, the matter is very well resolved. The sciatic nerve is a historical prohibition like leavened food, and as such it is clear that there is nothing repugnant about the nerve. Therefore Maimonides holds that the prohibition against eating the nerve is a prohibition of the act of eating and not a prohibition of benefit through eating. Accordingly, one cannot derive from the eating prohibition that there is here a prohibition of benefit as well, exactly as we saw in the case of leavened food. A possible source for this is again the passage in Beitzah, which shows us that even if one rules like Rabbi Abbahu, historical prohibitions can still be defined as prohibitions of action rather than prohibitions of benefit, as in the case of leavened food. The passage in Pesahim, which does not do this, is not adopted by Maimonides as practical law, because he decides in accordance with the passage in Beitzah. Accordingly, regarding the sciatic nerve too he maintains that even Rabbi Abbahu agrees with Hezekiah that it is permitted for benefit, because this is a historical prohibition and not one based on spiritual defect like the other eating prohibitions. If so, here too Maimonides is consistent with his broader view, and this difficulty provides significant confirmation of our hypothesis that the basis of his remarks is the historical background of the prohibition.

We thus learn that according to Maimonides, both in the case of leavened food and in the case of the sciatic nerve, he departs from his general ruling in accordance with Rabbi Abbahu. That is, in his view, even if one understands ordinary eating prohibitions in accordance with Rabbi Abbahu, these two prohibitions, both of which are historically grounded and both of which were stated even regarding something unfit for eating, are prohibitions of the act of eating and not prohibitions of benefit through eating, and therefore they do not necessarily entail a prohibition of benefit. In the case of leavened food we have a separate source that prohibits benefit, and therefore in practice it is prohibited for benefit as well. But in the case of the sciatic nerve there is no such source, and therefore it is permitted for benefit in practical Jewish law.

The prohibition of meat cooked in milk

We saw above that the definition of the prohibition of meat cooked in milk is similar to these two. Why is its halakhic definition too one of an act of eating rather than benefit through eating? It does not seem to have a historical background. Although our subject here is not the reason for the verse as such, we are interested in the relation between the reason and the definition of the prohibition, and therefore it is worthwhile to ask why meat cooked in milk was prohibited to us.

First, it is quite clear that here too the prohibition is not due to repugnance, for both the meat and the milk are themselves permitted for eating. Moreover, without cooking there is no Torah prohibition against eating meat cooked in milk. What then is the conceptual basis of the prohibition?

The Sefer HaChinukh, in commandment 92, writes concerning the reason for the prohibition of cooking meat in milk:

Among the roots of this commandment, it appears to be similar to what we wrote regarding the commandment concerning a sorceress, for there are things in the world whose mixtures are forbidden to us because of the reason we mentioned there; and it is possible that the mixing of meat with milk through cooking is the cause of its prohibition from that same underlying principle.

What does he mean? In commandment 62 he explains the prohibition of sorcery, and several prohibitions whose theme is the prevention of mixtures, as follows:

And the matter of sorcery, in my opinion, is as follows: the blessed God, at the beginning of creation, assigned to each and every thing in the world a nature by which to perform its proper and upright function for the benefit of the creatures of the world He created, and He commanded each one to act according to its kind, as is written in the portion of Genesis, “according to its kind,” regarding created things. And over each one He also appointed a heavenly force to compel it in its action, as the Sages of blessed memory said: “There is no blade of grass below that does not have a constellation above that says to it: Grow.” Now, beyond the action that each thing performs by its own nature, they also have another effect when one kind is mixed with another, and in the craft of such mixtures there are aspects that human beings were not permitted to use, because God knows that the eventual result for people from those aspects is harmful to them, and therefore He withheld them from us. This is the general meaning of what the Sages of blessed memory said: “Anything that has a medicinal purpose is not included in the ways of the Amorites”—that is, it is not to be forbidden on account of sorcery; once there is a real, experimentally verified benefit in it, it does not belong to the prohibited category, for those were forbidden only because of the harm involved in them.

There is yet another element in those prohibited mixtures and contrivances for which they were forbidden. The power of such a mixture rises so greatly that it temporarily nullifies the force of the heavenly influence appointed over the two species. An example of this is that when one grafts one species onto another, they produce a third species; thus the grafting has nullified the power of both. Therefore we were prevented even from contemplating—let alone doing with our own hands—something that would display in us a desire to alter anything in the perfect works of God. It is possible that from this we may gain an allusion to some of the roots of the prohibitions of mixed seeds, mixed breeding of animals, and shatnez, and in their proper place we will elaborate on them, with God's help. This is what the Sages of blessed memory meant when they said: “Why are they called kishuf? Because they weaken the heavenly entourage above and below”—that is, their power rises temporarily above the force of those appointed over them. Notice the precision of the Sages’ words: they said “the entourage above,” and did not say “the decree from above,” because the blessed God Himself decreed and willed from the beginning of creation that this effect should emerge from the combination of the two when they are mixed, and in that there is an open rebuke to those appointed over them; but they nevertheless said that the force of the entourage is, in any event, weakened. One whose intellect is close to the light of the King’s face, and whose meritorious power rises above that of the appointed forces, need not fear this act and its denials, as we find in the Talmud in tractate Shabbat, where the Sage said to the sorceress.

He explains that the mixing of two things causes a mixing of the spiritual forces appointed over them, and therefore it is prohibited.

Now let us return to commandment 92, where the Sefer HaChinukh explains that from his remarks it follows that the basis of the prohibition of meat cooked in milk is not the repugnance of this mixture. He brings proof of this from the fact that eating it is prohibited even when done not in the normal manner of enjoyment, exactly as we argued above with respect to leavened food and the sciatic nerve:

There is also some proof for this from the fact that the prohibition was imposed upon us with respect to the act of mixing, even though we have not eaten it, which shows that its prohibition is not at all due to the harm of eating it, but rather that the very act of making that mixture should not be done, in order to distance us from the matter we mentioned. And elsewhere He also warned us that if the mixture was in fact made, we must neither eat it nor derive benefit from it, again to distance us from that matter. Even if one ate it without deriving any benefit at all, he is lashed—unlike all other food prohibitions. All this indicates that the root reason lies in the mixture itself, as we said regarding sorcery.

The matter is explicit in the Sefer HaChinukh: eating is prohibited even not in the normal manner of enjoyment because the prohibition is not based on repugnance but is an obligation directed at the person. Our basic argument, according to which the definition of the prohibition, as one on the act of eating and not on the enjoyment of eating, with the practical consequence for one who eats not in the normal manner of enjoyment, follows from the fact that we are not dealing with a repugnant food but with some different underlying idea.

We have seen that the prohibitions of leavened food, the sciatic nerve, and meat cooked in milk are not prohibitions based on repugnance, and therefore what they prohibit is not the enjoyment of eating but the act of eating. From this it follows that one is liable even when eating them not in the normal manner of enjoyment.

This is the place to note that Maimonides writes in ch. 14 of Hilkhot Ma'akhalot Asurot, halakhah 10:

For all prohibited foods, one is liable only if he eats them in a manner of enjoyment, except for meat with milk and a vineyard mixture, because with them Scripture did not use the ordinary language of eating, but expressed their eating prohibition in other language—through the language of cooking and through the language of consecration—to prohibit them even not in the ordinary manner of benefit.

Regarding meat cooked in milk, these are the points we have already seen above. And mixed plantings of the vineyard are likewise a prohibition that results from mixture, as in the Sefer HaChinukh's reasoning above.

In light of our discussion above, there is room to ask why Maimonides omitted leaven and the sciatic nerve, for although they are not mixture prohibitions but historical prohibitions, one should seemingly also be liable for them when they are eaten not in the normal manner of enjoyment. Several later authorities have already noted this and proved from here that according to Maimonides, even regarding leaven and the nerve, which are not fit for eating in themselves, Maimonides exempts when they are eaten not in the normal manner of eating. See Shoshanat Ha'Amakim principle 9, the second passage beginning 'Know'; Ginat Veradim principle 45, the passage beginning 'Further'; Pri Megadim Yoreh De'ah sec. 62 subsec. 1; and Avi Ezri, Hilkhot Avot HaTum'ah ch. 1 end of halakhah 7.

One might have explained this on the basis of what the Avnei Nezer writes in sec. 349 subsec. 19, that Maimonides here in halakhah 10 is speaking of prohibitions that are fit for eating in themselves, and nevertheless if one eats them not in the normal manner of enjoyment he is not liable. But leaven, and one may add the sciatic nerve, are not fit for eating in themselves, and therefore that is not what he is addressing here.

But it seems more plausible to explain, following the Sha'agat Aryeh sec. 75 cited above, and see also Rashash on Beitzah 7b, s.v. 'There, however, leaven', that Maimonides means only eating in a way that is not the normal manner of enjoyment, and in that respect leaven and the sciatic nerve are indeed exempt. But this does not apply to something unfit for eating in itself. In that case meat cooked in milk is exempt, whereas in the case of the sciatic nerve and leaven one is liable for eating them.

The basis of this distinction is that eating not in the normal manner of enjoyment is not considered an act of eating, and therefore it exempts even in the case of the sciatic nerve and leavened food, since in those prohibitions the definition is to perform an act of eating. But a thing's being unfit for eating removes its name, and in that respect we are not concerned with this in leavened food and the sciatic nerve, since they are originally not fit for eating. If so, even in the case of leaven and the sciatic nerve, from the standpoint of the manner of eating one must eat them in their normal manner, and only the fact that they are unfit does not exempt, as we explained above.

If so, Maimonides' words here do not contradict our argument. In the case of meat cooked in milk one is liable even when he ate it not in its normal manner of enjoyment, because even the prohibition of eating there stems from the prohibition of mixture, the cooking in the case of meat cooked in milk and the grafting in the case of mixed plantings of the vineyard, and not from an ordinary eating prohibition based on the repugnance of the prohibited thing. The Sefer HaChinukh states this explicitly regarding meat cooked in milk in commandment 113, and regarding mixed plantings of the vineyard in commandment 549.[10]

From our standpoint, the meaning of the matter is that there the enjoyment of eating was indeed not prohibited, but nor is specifically an act of eating required. Therefore eating not in the normal manner, which is not considered an act of eating, does not exempt in those cases. In fact, with meat cooked in milk and mixed plantings of the vineyard this is only an extension of the prohibition of mixture itself. If so, in the case of meat cooked in milk and mixed plantings of the vineyard the definition of the prohibition is not exactly a prohibition of the act of eating, but perhaps something more like an act of consumption or use of the problematic mixture, and therefore even if one ate them not in the normal manner of enjoyment he is not exempt. This is unlike leavened food and the sciatic nerve, where the definition of the prohibition is specifically a prohibition of the act of eating.

We thus learn that there are three kinds of eating prohibition. The prohibitions of meat cooked in milk and mixed plantings of the vineyard are prohibitions against use of a forbidden mixture. The prohibitions of leavened food and the sciatic nerve are prohibitions against the act of eating. And ordinary eating prohibitions are prohibitions against enjoyment through eating. Therefore, in ordinary eating prohibitions one is exempt both when the thing is unfit for food and when one ate it not in the normal manner of enjoyment. In mixed plantings of the vineyard and meat cooked in milk one is liable in both cases. And in leavened food and the sciatic nerve one is exempt when one ate them not in their normal manner, but one is not exempt when one ate something unfit for eating, so long as the designation of the prohibition still remains upon it, as with leaven or with the sciatic nerve before it has lost that designation by nullification and the like.[11]

The law of a half-measure

In the passage in Yoma 74a, Rabbi Yohanan and Reish Lakish dispute the law of a half-measure, whether it is prohibited by Torah law, according to Rabbi Yohanan, or only rabbinically, according to Reish Lakish. In practice, all the decisors rule like Rabbi Yohanan, that a half-measure is prohibited by Torah law.

Now in ch. 1 of Hilkhot Hametz u-Matzah, halakhah 7, Maimonides brings the law of a half-measure with respect to leavened food:

One who eats any amount whatsoever of the leaven itself on Passover, this is prohibited by Torah law, as it says: “Leaven shall not be eaten.” Even so, he is liable to neither karet nor an offering unless he eats the requisite amount, which is an olive-bulk. One who intentionally eats less than an olive-bulk is given disciplinary flogging.

Maimonides prohibits a half-measure of leavened food by Torah law, apparently consistent with his view that he rules like Rabbi Yohanan. But here too the same difficulty arises that we saw above, for Maimonides takes the trouble to cite here an explicit source that teaches the prohibition of a half-measure with regard to leavened food, and does not suffice with the sources brought in the passage in Yoma for the general prohibition of a half-measure.

And indeed, here too the Kesef Mishneh noticed this and raised the question against Maimonides:

“One who eats from the leaven itself on Passover,” etc.—as it says, “It shall not be eaten.” It is difficult for me: why do we need a verse regarding leaven on Passover, when for all prohibitions in the Torah we maintain that a partial measure is prohibited by Torah law? Another difficulty: if derived from the verse, we should rather learn the opposite from it, for “it shall not be eaten” implies a full measure of eating. This requires further analysis. And regarding what he wrote, “one who eats less than an olive-bulk intentionally,” etc.—it is difficult for me: why speak of less than an olive-bulk, when we are discussing one who eats any amount whatsoever? It seems to me that since at the beginning of the clause he wrote, “one who eats any amount whatsoever of leaven is prohibited by Torah law,” implying even the slightest act of eating with no enjoyment at all, he comes here to teach us that although there is indeed a prohibition, there is no disciplinary flogging unless it is something from which his throat derives at least some benefit—that is, something fit to be called less than an olive-bulk. But this is difficult: what boundary is there between the two? And further, from where does he derive such a distinction? This requires further analysis.

Here he can no longer force an explanation, as he did with Maimonides' words in halakhah 2 regarding the prohibition of benefit, and he remains with the difficulty unresolved. He raises the possibility of distinguishing between an amount that gives some slight enjoyment and an amount that gives no enjoyment at all, but even this seems forced to him. This distinction too is offered in accordance with his own understanding of Maimonides, for he assumes that Maimonides sees the prohibition of eating leavened food as an ordinary eating prohibition. Other later authorities suggested various explanations of Maimonides, but nearly all of them are forced.

According to our approach, however, the matter is very well resolved. We saw that Maimonides understands the prohibition of eating leavened food as a prohibition of the act of eating, not as a prohibition of enjoyment by means of eating. If so, we have here a prohibition of action and not an object-prohibition, and later authorities wrote that the law of a half-measure does not apply to prohibitions of action.[12] The reasoning is that the law of a half-measure is based on the logic that it is fit to combine: if two half-measures were eaten, then in the end a full measure was eaten and a Torah prohibition was violated. But this assumes that the prohibition is enjoyment from the forbidden item, and when one derives enjoyment from two half-measures, in the end there is enjoyment from a full measure. But with two half-acts, each one is not a partial act at all, because an act has no half, only an object has a half. For example, one who throws an object two cubits in the public domain has not performed half an act of throwing, but no prohibited act of throwing at all. If so, the ordinary law of a half-measure cannot teach us about the prohibition against eating leavened food, because this is a prohibition against the act of eating and not against enjoyment from eating.[13]

The Kesef Mishneh, who understood the prohibition against eating leavened food differently, as we saw in his remarks on halakhah 2, therefore remained here too with an unresolved difficulty. But according to our approach, in both of these halakhot Maimonides' unique conception of the prohibition against eating leavened food is expressed. Therefore there is also no room for the distinction he proposed here between eating something tiny that gives no enjoyment at all and eating something else, because the basis of the prohibition is not enjoyment. We shall return to this implication below.

It is worth citing here the words of the Maharalnaḥ, as brought by the Mishneh LaMelekh on this halakhah:

And I saw that Rabbi Maharalnach, in responsum no. 51, was troubled by this very question of Maran of blessed memory, and answered that the prohibition of leaven is not comparable to forbidden fat, from which they learned that a partial measure is prohibited, because forbidden fat is prohibited forever and never had a time of permissibility; this is not so for leaven, which is permitted before Passover. Therefore, a separate verse was needed with regard to leaven to prohibit a partial measure (before Passover)…

The Maharalnaḥ argues that the prohibition of a half-measure was not stated regarding prohibitions that depend on time, but only regarding permanent prohibitions. But Rabbi Zolti already objected to him in Mishnat Yaavetz, Orah Hayyim sec. 14, that the eating prohibitions of Yom Kippur are also time-dependent, and that this is precisely the subject of the half-measure passage in Yoma. So how can the Maharalnaḥ claim that the law of a half-measure was not stated for temporary prohibitions? It is indeed astonishing that he did not notice so simple a difficulty.[14]

But according to our approach, it is possible that the Maharalnaḥ's words too fit very well. His intent may be to argue that the prohibition of leavened food is not due to its being repugnant, as in the case of other eating prohibitions, since leavened food is permitted for eating and benefit before and after Passover. If so, the fact that it has a period of permissibility proves that it is not repugnant in itself, and that is precisely the argument we advanced above in explaining Maimonides. From this it follows that the basis of the prohibition is not enjoyment from leavened food, but the performance of an act of eating upon it, as we argued above. That is why an additional source is required in order to prohibit a half-measure of leavened food. We can now understand that the objection raised against him from the prohibitions of Yom Kippur is not difficult at all. The prohibitions of Yom Kippur are indeed time-dependent, but there it is clear that the prohibition is to derive enjoyment from eating, because the basis of the prohibition is the obligation to fast. Fasting by definition is the prevention of enjoyment, and therefore although the prohibition is temporary, it is clear that its essence is eating that brings enjoyment and not the act of eating as such. Accordingly, it is obvious that the law of a half-measure applies there, just as it does with forbidden fat, because enjoyments do combine, as stated above.

A similar consideration can be raised regarding meat cooked in milk. There too we saw that according to Maimonides the prohibition is on the act of eating and not on benefit from eating, and therefore one is liable even when one eats it not in the normal manner of enjoyment. And the reason is that meat cooked in milk has a period of permissibility, for milk and meat separately may be eaten and there is nothing repugnant about them. Only their mixture is prohibited, and therefore this proves that the prohibition is not due to their repugnance, but is merely a prohibition of action.[15]

And what about the sciatic nerve? In Minhat Hinukh, commandment 3, he cites in the name of the Pri Megadim, in Mishbetzot Yoreh De'ah sec. 65 subsec. 4, a major innovation: if one ate half an olive-bulk of the nerve, then tarried long enough for the time needed to eat a standard portion, and then ate another half olive-bulk, one is not liable. They explain that the prohibition of the sciatic nerve is a novelty, for even though its taste is like wood one is still liable for it, and a novelty extends only as far as its own innovation. They derive this from limb torn from a living animal, see there. They further raise the possibility that there is no prohibition of a half-measure regarding the nerve, because the logic that it is fit to combine does not apply to it.[16]

According to our approach, the matter is even better resolved, for a half-measure in prohibitions such as leavened food and the sciatic nerve requires a special innovation. In the case of leavened food we found a verse that teaches the prohibition of a half-measure, and therefore a half-measure is prohibited there. But in the case of the sciatic nerve there is no such verse, and therefore there is no prohibition of a half-measure there. The explanation is that the logic that it is fit to combine does not apply here, because there is no combining of half-acts, as we saw regarding leavened food. This is exactly the same situation as with the prohibition of benefit. In the case of leavened food it is learned from that same verse itself, 'it shall not be eaten', whereas in the case of the sciatic nerve we have no source, and therefore there is no such prohibition.

It is interesting to note that similar considerations arise regarding meat cooked in milk as well.[17] Some wrote, see Pri Megadim, 'General Introduction' to Orah Hayyim part 1 subsec. 17, that meat cooked in milk is a novelty and therefore extends only as far as its innovation, and that a half-measure of it is not prohibited by Torah law, exactly as we saw regarding the sciatic nerve. According to our approach, here too the explanation is that the prohibition of meat cooked in milk is one on the act of eating, and therefore the logic that it is fit to combine does not apply here either.

A special prohibition regarding a mixture containing leavened food

Maimonides, in Sefer HaMitzvot, counts a special prohibition regarding a mixture containing leavened food, and Nahmanides objects to him. The matter is brought in Sefer HaChinukh, commandment 12, which writes as follows:

Not to eat anything that contains leaven

Not to eat things that contain leaven, even though the substance itself is not primarily leaven—for example, Babylonian kutah and the like—as it is said: “You shall eat no leavened thing.” And the Sages of blessed memory explained that this verse indicates precisely this, for so they received its interpretation.

Maimonides’ view, of blessed memory [in Sefer HaMitzvot here], is that if these foods contain an olive-bulk of leaven within the time needed to eat a half-loaf, it is prohibited by Torah law under a prohibition—meaning for lashes, though not karet—since it has been mixed into a majority. But if they do not contain an olive-bulk of leaven within the time needed to eat a half-loaf, there is no flogging, only disciplinary flogging, because it is not prohibited by Torah law but only rabbinically. So too he wrote in his major code. According to him, then, this prohibition of “any leavened thing” applies where an olive-bulk of leaven is mixed in within the time needed to eat a half-loaf, making it a prohibition carrying lashes, though not karet.

According to Maimonides there is a special prohibition, a separate negative commandment, against eating a mixture that contains leavened food. This is a distinct prohibition, and therefore Maimonides writes that it does not carry excision as ordinary eating of leavened food does. The lashes for this negative commandment are administered only where the mixture contains an olive-bulk of leavened food within the amount ordinarily eaten in the time known as kedei akhilat pras.

The Sefer HaChinukh continues there and reports that Nahmanides challenges Maimonides and disagrees with him:

But Nachmanides of blessed memory wrote the opposite of this [in his glosses here], and said that this prohibition is not counted among the distinct prohibitions, but is simply one of the several prohibitions stated concerning leaven and sourdough. This prohibition comes to teach what the Sages said in the Talmud: “I only know of dough that became leavened on its own; from where do we know if it was leavened by means of something else? Scripture therefore says: ‘any leavened thing.’”

But with regard to leaven that is mixed in, whenever there is an olive-bulk within the time needed to eat a half-loaf, there is no need for a separate prohibition, for it is considered as though it were present in its own right, and it carries karet just like any leaven that is present in its own right. And if there is not an olive-bulk within the time needed to eat a half-loaf in the mixture, one who eats it is exempt, though it is forbidden, for the law follows the Sages, who said that only complete grain-leaven incurs karet; and anything containing an olive-bulk within the time needed to eat a half-loaf is called complete grain-leaven. But regarding its mixture—meaning where it is less than an olive-bulk within the time needed to eat a half-loaf—there is nothing at all. This is not in accordance with Rabbi Eliezer, who disagrees with them in the Talmud and says that a mixture incurs a prohibition carrying lashes.

He writes that if the mixture contains an olive-bulk of leavened food within kedei akhilat pras, then this is simply the ordinary prohibition of eating leavened food, and there is no need for a special negative commandment in order to prohibit it. A person who ate such a mixture has eaten an olive-bulk of leavened food within kedei akhilat pras, so why should that not be included within the ordinary prohibition against eating leavened food? Nahmanides therefore concludes that in such a case one is certainly liable to excision, and that this negative commandment teaches a detail within the prohibition of eating leavened food, namely that it applies even when the leavening occurred through something else and not on its own.

What is the basis of the dispute? It seems that here too Maimonides is following his own general approach. Nahmanides' claim is based on the assumption that the prohibition against eating leavened food is an ordinary eating prohibition, that is, a prohibition against deriving enjoyment through eating leavened food. Therefore, if such a mixture was eaten, then an olive-bulk of leavened food was eaten here, meaning that this person derived enjoyment through eating an olive-bulk of leavened food, and therefore it is obvious that he is liable to excision. By contrast, Maimonides holds that this is a prohibition on the act of eating something called 'leavened food', and therefore the fact that an olive-bulk of leavened food entered my body does not yet mean that I violated the prohibition. The question is whether such an act counts as an act of eating performed on the leavened food, or whether it is rather an act of eating a mixture, which does not bear the designation 'leavened food', during which an olive-bulk of leavened food was also consumed. This cannot be learned from the ordinary prohibition of eating leavened food, and therefore according to Maimonides a special source is required to teach it.

Nullification of taste

We can now understand the other side of the coin as well. Once it has been innovated that even a mixture containing leavened food is called 'leavened food' and is subject to a prohibition of eating, there is now room to prohibit even a mixture in which the leavened food does not impart flavor. That is, a mixture containing a very small amount, less than one part in sixty, of leavened food, in which there is no taste of leavened food. In practical Jewish law, it is accepted that leavened food on Passover is prohibited even in the slightest amount, that is, there is no ordinary nullification regarding the prohibition of leavened food. The reason is that nullification operates on the taste of the prohibition, and in all ordinary eating prohibitions the prohibition is to derive enjoyment from the taste of the forbidden item, and when that taste is nullified there is no enjoyment from eating the prohibition. But in the case of leavened food the prohibition is on the act of eating, and once it has been innovated that even a mixture has the status of leavened food, and that one who eats a mixture is considered to have eaten leavened food, there is no significance to the questions of quantity and taste. So long as there was leavened food in the mixture, the person ate it, and therefore violated the prohibition against eating leavened food. According to Maimonides, of course, this refers to the special prohibition discussed in the previous section, and not to the prohibition of eating intact leavened food, which incurs excision.

True, it is commonly assumed that the rule that leavened food on Passover is prohibited even in the slightest amount is only rabbinic, but even on that view the matter can be explained. When the taste is nullified, the mixture is no longer considered a mixture of leavened food at all, and the leavened food in it has lost its designation as a result of the nullification of taste. Therefore there is no act of eating leavened food, or even a mixture of leavened food, here, and accordingly there is no Torah prohibition, just as we saw regarding leavened food that is unfit for eating. Nevertheless, because the basis of the prohibition against eating leavened food is a prohibition against the act of eating leavened food, and not benefit from the taste of leavened food, the Sages still saw fit to prohibit this rabbinically.

From this it also becomes clear why the distinction proposed above by the Kesef Mishneh is incorrect, namely, between eating some tiny amount that gives no enjoyment at all and eating less than an olive-bulk which does give enjoyment. According to our approach to Maimonides, there is no prohibition of enjoyment here. The only question is whether an act of eating is being performed upon an object that still bears the designation 'leavened food'. Therefore, so long as that designation remains, irrespective of the degree of enjoyment, there is a prohibition of eating here. Only where the leavened food in the mixture loses its name under the laws of nullification of prohibitions is there no Torah prohibition.

And this is what Maimonides writes at the beginning of ch. 16 of Hilkhot Ma'akhalot Asurot, based on the passage in Hullin 99b:

1. All these measures that the Sages gave regarding a forbidden substance mixed with a permitted substance of the same type apply only where the forbidden substance was not a leavening agent, not a seasoning, and not an important item that remains intact as it is and was not mixed in and blended with the permitted substance. But if it was a leavening agent, a seasoning, or an important item, it renders the mixture forbidden in any amount whatsoever.

2. How so? If wheat sourdough of terumah fell into dough of ordinary wheat, and there is enough in it to leaven it, the entire dough becomes meduma. Likewise, if spices of terumah fell into a pot of ordinary food, and there is enough in them to season it, and they are of the same type as the ordinary food, everything becomes meduma, even if the sourdough or the spices are only one part in a thousand. Likewise, if sourdough from a vineyard mixture fell into dough, or spices of orlah into a pot, everything is prohibited for benefit.

We see that leaven is not nullified even in the slightest amount. The commentators there discuss whether this is a rule of a significant item, see Yad HaMelekh and others, but according to our approach it may be a special rule regarding leaven because of the nature of the prohibition.[18]

And indeed, we find the same with the sciatic nerve. As we saw, there too the definition of the prohibition is one on the act of eating and not on enjoyment, and the nerve has no taste, and therefore it too is not nullified in the ordinary way, for taste is irrelevant in its case. According to our approach, the law should really have been that the sciatic nerve is never nullified at all. But as we saw with respect to leavened food, there is a kind of nullification that removes from it the designation of the prohibition even without regard to taste, and therefore the rule that leavened food on Passover is prohibited even in the slightest amount is only rabbinic. And in ch. 15 of Hilkhot Ma'akhalot Asurot, halakhah 9, Maimonides explains this by saying that it is a prohibition that will eventually become permitted, which implies that without that factor it would be subject to nullification. We are therefore compelled to say that by Torah law there is nullification here even without considerations of taste, because the nullification removes the designation 'leavened food' from it, and therefore there is no act of eating leavened food here.

And indeed, with regard to the sciatic nerve as well, we find in the Mishnah Hullin 96b a special measure for nullification:

Mishnah: A thigh in which the sciatic nerve was cooked—if it contains enough to impart flavor, it is forbidden. How is this measured? Like meat with turnips.

What is this turnip-measure?[19] Some explained it as sixty, or as the ordinary criterion of imparting taste. But the plain meaning of the Mishnah is that this is a measure unrelated to taste and to the ordinary measures of nullification. It is possible that here we have a measure beyond which the sciatic nerve no longer retains its name, and therefore it is nullified. Accordingly, when one eats it there is no act of eating the sciatic nerve, and therefore it is permitted.[20]

Another interesting implication can be found in the dispute among the medieval authorities regarding the fat of the sciatic nerve. The fat of the nerve does have flavor, and nevertheless some of the medieval authorities claimed that it does not prohibit its mixture by imparting taste. See Tosafot s.v. 'Im Yesh', Hullin 89b; Tosafot s.v. 'Shani', 97a; Tosafot s.v. 'Ve-Hilkhata', 99b; the Meiri there; and Rashba in Torat HaBayit, House 3 Gate 3, and others. The explanation they offer is that the fat is prohibited because of the nerve itself, and just as the nerve does not prohibit through taste, since it has no taste, so too the fat. The Meiri wrote that the secondary element should not be more stringent than the primary one.[21]

But this is still difficult, for the reason the nerve does not prohibit by taste is simply that it has no taste. What stringency is involved here? There is no special rule that the sciatic nerve does not prohibit through taste. If it had taste, it would prohibit. It is only that in practice it has no taste. But the fat does have taste, so why should it not prohibit?

We are therefore compelled to conclude that even in the case of the nerve, it does not prohibit by taste for an essential reason, and not only because in practice it has no taste. That is, even if it had taste it would not prohibit by taste. And that is precisely our point. The prohibition of the sciatic nerve is not a prohibition of enjoyment through eating, but a prohibition of the act of eating, and therefore taste is irrelevant to this prohibition. Even if it had taste, it would still not prohibit, because what is prohibited is eating the sciatic nerve and not deriving enjoyment from the taste of the sciatic nerve. Therefore, just as in the case of the sciatic nerve taste does not prohibit because of the character of the prohibition and not merely because in fact it has no taste, so too regarding its fat. Since the definition of the prohibition in the fat is the same definition, it does not prohibit even though in fact it has flavor. In the fat too, the prohibition is on the act of eating and not on enjoyment through eating, because its prohibition is due to the prohibition of the nerve. If so, this is not merely a question of secondary versus principal, but rather the halakhic definition of the eating prohibition regarding the fat of the sciatic nerve is certainly the same as the prohibition regarding the nerve itself, since in both cases the prohibition exists for the same historical reason. The prohibition of the fat is, of course, that very same prohibition, as a memorial to Jacob's struggle with the angel.

As for nullification of taste in meat cooked in milk, much more could be said, but here we shall cite only the words of the Sefer HaChinukh in commandment 113:

They were even more stringent in this matter, saying as well that according to some interpretations there is a novel prohibition here beyond other food prohibitions. In the case of meat with milk, if milk became mixed with meat and the piece of meat into which it was mixed does not contain sixty times the milk, we regard both together as a single forbidden piece. If that piece then falls into a pot of meat or a pot of milk, we measure against the entirety of the piece. This is what the Sages of blessed memory meant when they said: “The piece itself becomes like carcass-meat.” The reason is that their mixture itself renders them forbidden, and therefore once they have been mixed they are like a piece of carcass-meat. In other prohibitions this is not so: if a forbidden substance became mixed into a permitted piece, and the piece does not contain sixty times the prohibition to nullify it, and that piece then fell into a pot, we measure only according to the amount of the original prohibition that fell in, and the piece itself helps to nullify the prohibition, because that piece itself did not become like carcass-meat. The permitted part within it is therefore treated like the rest of the permitted contents of the pot and helps nullify the prohibition. The piece itself, however, if identifiable, remains forbidden forever according to some commentators.

We see that even in the case of meat cooked in milk there is a stringency regarding nullification, and these matters are connected to the meaning assigned here to that prohibition. With meat cooked in milk too the question is not whether there is the taste of meat and milk, but whether there is here a mixture of the two things. If there is, then there is an act of eating a mixture of meat cooked in milk. But if one of the two is halakhically treated as absent, then there is no prohibition.

Conclusion

In this article we have seen that there are several exceptional eating prohibitions, and we have examined the halakhic consequences of that exceptional character. Ordinary eating prohibitions are prohibitions of enjoyment through eating, in practical Jewish law because we rule like Rabbi Abbahu, and not necessarily prohibitions of the act of eating. The prohibitions of mixed plantings of the vineyard and meat cooked in milk are prohibitions on using a problematic mixture, not necessarily by way of eating, and therefore they do not have an exemption when consumed not in the normal manner of enjoyment or when they are unfit for eating. Leavened food on Passover and the sciatic nerve are prohibitions whose basis is historical, and therefore their concern is not to perform an act of eating upon something whose name is 'leavened food' or 'the sciatic nerve'. Therefore they do have an exemption when one ate them not in the normal manner, because that is not an act of eating. But they do not have an exemption when they are unfit for eating, so long as their designation remains upon them, for in such a case an act of eating has been performed upon something whose designation is 'leavened food' or 'the sciatic nerve', and therefore the Torah prohibition has been violated. Only where that designation falls away is there an exemption regarding eating them.

We saw several implications of these distinctions, such as the law of a half-measure, which according to several views among the decisors does not apply to prohibitions of this kind, or at least requires a special source; the nullification of the taste of a prohibition; the prohibition of eating a mixture containing a prohibited item; and also the existence of a prohibition of benefit, which in these cases does not follow from the eating prohibition, and therefore either does not exist or requires a special source, even according to the authorities who follow Rabbi Abbahu's view that eating prohibitions always entail prohibitions of benefit, except in cases where the Torah itself excluded this, as in the case of carrion.

[1]  Admittedly, in the dispute between Maimonides and the Ra'avad, Hilkhot Hametz u-Matzah ch. 1 halakhah 2, it appears that some disagreed about this and held that leaven is fit for a dog's consumption, and in certain cases perhaps even for human consumption, and the commentators there have already discussed this at length.

[2]  However, the Sha'agat Aryeh, sec. 75, wrote the opposite, and in his view eating not in the normal manner of enjoyment is more severe than eating something unfit for consumption. See there. Below we shall return to this point.

[3]  See Shulchan Arukh sec. 442:9 and the commentators there. We shall not enter here into the law of hardened leavened food and moldy bread, which according to some views may present an exception in this regard.

[4]  See Avnei Nezer Orah Hayyim sec. 349, who discussed this at length, and likewise the Bi'ur Halakhah on the Shulchan Arukh there. Below we shall mention his remarks.

[5]  In light of the conclusion that Beit Hillel and Beit Shammai disagree over whether removal is learned from eating or not, one may ask what place remains for the arguments raised at the beginning of the passage concerning the superfluity of the word 'leaven'. Briefly, we may say that the dispute whether removal is learned from eating is not a dispute about methods of exegesis but about the essence of the prohibition of removal. According to Beit Hillel, the obligation of removal exists lest one come to eat it, whereas according to Beit Shammai it is an independent prohibition. See on this in Lekach Tov, by Rabbi Yosef Engel, at the beginning of principle 8.

We can now understand that according to Beit Shammai, when one is dealing with removal, the fact that the thing is unfit for eating has no significance, and only the question whether it is considered leavened food matters. By contrast, according to Beit Hillel, fitness for eating determines the duty of removal as well, and therefore if the Torah had written removal with respect to leavened food, we could not have learned a duty of removal regarding leaven, because perhaps in the case of leaven there is no concern that one may come to eat it, and therefore there is no obligation to remove it. Hence the dispute over whether removal is learned from eating is what underlies the considerations presented at the beginning of the passage, only this time with respect to removal, and not, as was initially thought, with respect to the prohibition of eating.

[6]  See also there in halakhah 11 regarding laundering and stirring.

[7]  I later saw that in Ahiezer, Yoreh De'ah sec. 11, he elaborated on this reasoning and its implications in other halakhic contexts as well, such as leaven of terumah and with respect to other prohibitions. See also Avnei Nezer Orah Hayyim sec. 349, who discussed at length the law of leavened food that has become more fermented and is fit for leavening other doughs, whose law differs from the law of leaven.

[8]  To be sure, there is an additional verse that prohibits leavened food for benefit as well, but this is an additional prohibition. It is highly plausible that the prohibition of benefit too is not because leavened food is repugnant, but that it is likewise a reenactment of the condition that existed at the Exodus from Egypt. The Israelites did not benefit from leavened food, and we too are not meant to benefit from it.

[9]  I later saw that the author of the Bi'ur Halakhah, sec. 442:9, bases Maimonides' view in halakhah 2 on exactly this reasoning, and he adds that the Ra'avad there disagrees with him on this point, though his remarks regarding the Ra'avad's view do not seem conclusive.

[10]  See Avodah Zarah 66a in the view of Rabbi Meir, who sees all eating prohibitions in this manner, that they result from having been rendered abominable by prohibition and not from the repugnance of each one for a different reason, and therefore he holds that they combine with one another.

[11]  However, this line of thought seems at first glance problematic for explaining Maimonides' view, because in halakhah 11 there he writes:

How so? If one melted the forbidden fat and swallowed it while it was hot, so that it scorched his throat, or if he ate raw forbidden fat; or if he mixed bitter substances such as gall or wormwood into libation wine or into a pot of carcass-meat and ate them while they were bitter; or if he ate prohibited food after it had spoiled and become putrid and was no longer fit for human consumption—he is exempt. But if he mixed a bitter substance into a pot of meat cooked with milk, or into wine from a vineyard mixture, and ate it, he is liable.

We see that even something unfit for eating is included under the heading of eating not in the normal manner of enjoyment. But here it is clear that leaven and the sciatic nerve are not included, for they are certainly not fit for eating. And indeed, later authorities already noted that Maimonides here conflated something spoiled and unfit for human consumption with eating not in the normal manner of enjoyment. See Noda B'Yehuda, first edition, Yoreh De'ah sec. 26; Havot Da'at sec. 103 subsec. 1; Pri Megadim sec. 442; and others. Therefore one must say that Maimonides mentioned the law of something spoiled and no longer fit for human food only incidentally, but in truth the law of something unfit for eating is different from the law of eating not in the normal manner of enjoyment. We can now explain why in halakhah 10 he omitted leaven and the sciatic nerve, following the Sha'agat Aryeh, as stated above, and the law of something unfit for eating certainly does not apply to leaven and the sciatic nerve, as stated above.

[12]  This is true not only according to the singular view of the Hakham Tzvi, sec. 86, who holds that the law of a half-measure was stated only regarding eating prohibitions, but even according to the views that disagree with him, in prohibitions of action there is no law of a half-measure. For example, one who throws an object only two cubits in the public domain on the Sabbath, or one who uproots without placing down, or the reverse, in the prohibition of carrying on the Sabbath. See on this the Sefat Emet, Shabbat 2a, regarding the prohibition of half a labor on the Sabbath, and much more. To be sure, one can distinguish between performing half a labor whose other half is of a different character, such as uprooting without placing down, and throwing two cubits in the public domain, which is in fact identical to the other half. See on this at length in the Encyclopedia Talmudit, entry 'Half-measure', especially ch. 3, but this is not the place to expand.

[13]  This may be compared to a half-measure in Sabbath labors that are performed on objects, such as carrying out. See on this the Mishneh LaMelekh at the beginning of ch. 18 of Hilkhot Shabbat and elsewhere.

[14]  I later found a long discussion and many sources on this in the Encyclopedia Talmudit, entry 'Half-measure', between notes 503-525, and also in notes 445-448 regarding meat cooked in milk.

[15]  This can be proved from the passage in Hullin 115b, where it is shown that the prohibition of meat cooked in milk counts as something that had a period of permissibility. But there the meaning may be different, because perhaps there the period of permissibility is itself the subject of the discussion, and not merely an indication of the nature of the prohibition, at least not for the question whether this is a prohibition of action or an object-prohibition. To sharpen the point, let us say that even if there we had found that meat cooked in milk had no period of permissibility, that would not have proved anything for our discussion here. What matters for our purposes is that meat and milk are not repugnant, and therefore this is not a standard prohibition of repugnant food. As we saw in the Maharalnaḥ, the existence of a period of permissibility is for us here only an indication of the nature of the prohibition, not the criterion itself. See the Encyclopedia Talmudit, entry 'Half-measure', around notes 445-448.

[16]  See the Encyclopedia Talmudit, entry 'Sciatic Nerve', note 184, for the objection raised against them from Rashi and the Meiri on 83a, and its resolution. See also responsa Ketav Sofer, Yoreh De'ah sec. 34, who rejects the proof from limb torn from a living animal. But according to our approach, this has no connection at all to limb torn from a living animal.

[17]  See the Encyclopedia Talmudit, entry 'Half-measure', notes 444-466.

[18]  It still requires consideration why in the case of meat cooked in milk there is nullification by taste. According to our approach, there too the prohibition is on the act of eating and not on enjoyment through eating, and therefore it would seem that the law of nullification should not apply there either.

But this is not difficult at all. With meat cooked in milk and with the sciatic nerve we do not find an additional verse that innovates that even a mixture bears the designation 'meat cooked in milk' or 'sciatic nerve', as we found in the case of leavened food. Therefore, the further stringency that even rabbinically any amount should be treated as though an act of eating had been performed was never innovated there, because as we explained above, that rabbinic decree follows from the character of the Torah prohibition. It follows that in the case of meat cooked in milk the law remains at its original level, like the basic Torah law of leavened food before the rabbinic decree that it should not be nullified even in the slightest amount. There, when the taste is absent, the designation 'leavened food' falls away, and therefore one has not eaten leavened food, and only the Sages prohibited it. The same is true of meat cooked in milk. When the taste is nullified, this is not a mixture of meat cooked in milk, and therefore the act of eating was not performed on a mixture of meat cooked in milk.

Further on the nullification of meat cooked in milk, see the words of the Sefer HaChinukh that are cited immediately below.

[19]  See the collection of explanations in the Encyclopedia Talmudit, entry 'Sciatic Nerve', ch. 7.

[20]  Let us note that this halakhah is not brought in Maimonides at all. However, in his Commentary on the Mishnah to Hullin, ch. 7 mishnah 4, he explains:

They said: like meat with turnips—meaning that it imparts some perceptible flavor, one that can be sensed by the faculty of taste, just as a person senses turnips cooked with meat when tasting them and can distinguish them from turnips cooked without meat, because meat affects the flavor of turnips in a way that other plants do not.

His claim is that this measure is the measure at which the meat imparts flavor into the sciatic nerve, and not the measure at which the taste of the prohibition is felt in the mixture, as is standard in the other prohibitions, where the measures of nullification are assessed according to the taste of the forbidden item. The reason is that in the case of the sciatic nerve we are looking for a measure that removes the designation 'sciatic nerve' from the prohibited item, not one that nullifies the taste of the prohibition. Accordingly, the measure of the meat's flavor in the nerve was stated for the purpose of removing from the mixture the designation 'sciatic nerve', and not for the purpose of nullifying the taste of the prohibition. This is precisely our point.

[21]  However, Maimonides in ch. 15 halakhah 17 of Hilkhot Ma'akhalot Asurot, quoted above, holds that the fat does prohibit in sixty. But in his view the fat of the sciatic nerve is prohibited only rabbinically, and therefore it is possible that the Sages fixed its definition on a uniform basis.