How the christ does the Y Combinator work?

Fuck, I've been rereading http://mvanier.livejournal.com/2897.html for the past several hours and it might as well be written in Esperanto. Am I just not cut out for EXPERT PROGRAMMING‽

>>17,20,21,28,etc
If you want to know why it's important, read the following keeping in mind that the constraints encountered are not arbitrary:
http://www.ps.uni-sb.de/courses/sem-prog97/material/YYWorks.ps

>>28:
Practically though, this is only syntactic sugar.
Terrible!