In our culture (at least because it owes to the Greeks, which is not little) to see was always synonymous with knowing. "See?" We ask our interlocutor when we want to make sure he has understood, that he has learned. The etymology of the Greek language teaches us that idea, eidos, the object of knowledge, and image, eidolon, the object of our vision, have the same root: see, idein. The same word idea, the eidos, before becoming the invisible entity par excellence of metaphysics (that is, a region that is beyond physics and its visibility) and before becoming the abstract concept of logic , Was, more specifically, the way of appearing.