Main: topics that are interesting to most LW readers, AND are notably worth reading
Discussion: topics that are interesting to most LW readers, OR are notably worth reading for some readers
Open Thread: everything else
It's not clear to me what category this post should fall under on that basis, but I'd suggest the heuristic that anything posted to Main which retains a positive score after a few days might as well stay there.
People want to tell everything instead of telling the best 15 words. They want to learn everything instead of the best 15 words. In this thread, instead post the best 15-words from a book you've read recently (or anything else). It has to stand on its own. It's not a summary, the whole value needs to be contained in those words.
I'll start in the comments below.
(Voted by the Schelling study group as the best exercise of the meeting.)