What's the most intellectually intense subject/skill you've tackled or taught yourself?

For me: teaching myself the mechanics of storytelling+screenplays last few years.

What have been your favorite resources  for learning about storytelling + screenplays?

growing gardens in the dark forest ❀✿❀
digitlartifacts.twitter

Lots of books ( save the cat, William Gibson, Robert McKay, etc). but the BEST way is to download pdfs of screenplays of movies you love, read them and then compare to the onscreen format.