I had to do a little bit of Prolog back in University, decades ago, and it broke my head.

I managed to actually solve all the programming tasks we were given (and as I was the only one to do so among my peers, many copied my solutions) - but if anyone then asked me to explain how I did it, I was at a loss. I basically stared at the screen until some sort of intuition hit, and if that didn't work, repeat the process until it does...

I guess the paradigm never really "kicked in" for me ;)