There's a quote I like from Terry Pratchett's juvenile book "Only You Can Save Mankind" that addresses a mistake that some people with a high IQ make:
"Just because you have a mind like a hammer doesn't mean you should treat everyone else like a nail."
That's 19 words (if you count "doesn't" as 1 word, rather than 2), but perhaps a 15 word version could be:
"Don't manipulate those you can out think, just because you are able to."
or, more abstractly,
"Don't treat people as inconvenient objects, even when you can get away with it."
"Don't manipulate those you can out think, just because you are able to."
Why?
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.)