What is revelation?

If God is transcendent without body and form, how can He be revealed to the eyes of flesh and blood?
And if the revelation is by God manifesting Himself in some way, what is the meaning of "I saw my back, but my face shall not be seen?" What is the difference between face and back, since both are a type of disguise? And why will He not be revealed to all the people in one way or another?
And as for the voice that spoke from the mist, again, this is because God made some kind of voice that would be heard by the people, embodied His voice in a way that would be heard by humans. Why did He have to speak the last eight commandments through Moses? Couldn't God adapt His voice to the audience?