“Aha!” moments

I just had one, reading SICP, looking at the coins code. I'd never really properly looked into it and thought it was kind of complex, but I just spent 15 minutes examining the code and I got it! Tackling an iterative version will be interesting.

ITT your last “aha!” moment

Note: if you don't remember when your last “aha!” moment was, perhaps you need to read SICP. (Or just consider that you really should.)

Understanding where the "We conjure the spirits" line was from.