Comment by Analemma_

If you've never worked through a derivation/explanation of the Y combinator, definitely find one (there are many across the internet) and work through it until the light bulb goes off. It's pretty incredible, it almost seems like "matter ex nihilo" which shouldn't work, and yet does.

It's one of those facts that tends to blow minds when it's first encountered, I can see why one would name a company after it.