A lot is made out of Rene Descartes metaphysical problems with dualism (the idea that mind and body and completely different, and cannot interact). Another problem that he created with his dualism is the problem of representation. If mind and body are two different things entirely, how does an image in our mind relation to a physical object at all?
We look at a deck of cards, and an image of cards appears in our minds, but if mind and matter are two entirely different things, how can one cause the other? More than that, if they aren't directly related, what is the difference between a "true" image of cards, and an image that appears true to us, but there are no cards (or just cards drawing on a page that fooled us). A lot of philosophers after Descartes came up with all sorts of wacky solutions. Malebranche, for example, said that God put the image into our minds every time, and we were actually seeing an image in God's mind, and he relates it to the physical body. Berkeley just got rid of the physical world entirely, and said all there really is are images. Leibniz more or less said it was only a coincidence that mind and body coincided.
We never really solved this problem, aside from just generally accepting that consciousness was part of the physical world, at least in some way. For Descartes, it wasn't just consciousness, it was a spiritual being that had to survive death, so it had to be totally cleavaged from the physical world. It has a lot of drawbacks philosophically for him, but it does make it easier to cheat at poker, so it evens out.
Yes, you do have to eat pieces of paper with pictures of sandwiches on them once it a while, but it's better than accept the alternative theories of truth, which can't fully explain how the mind and body are separate things.
The platonic dialogue Protagoras starts with a brief discussion of which young man in Athens is the fairest, and whether or not they look best with a beard. All of this is very strange and pointless, since it's just a setup for Socrates to obnoxiously say "but actually, isn't WISDOM even fairer??" as an introduction to Protagoras being in town.
I love the fact that for thousands of years books had to be meticulously hand copied, so monks had to carefully replicate how Socrates didn't mind if his loverboys had beards, like it was some important piece of philosophy.