God Preserve Us! Chekhov on Writing

From an 1886 letter written by Anton Chekhov:

"In the sphere of psychology, details are also the thing. God preserve us from commonplaces. Best of all is it to avoid depicting the hero's state of mind; you ought to try to make it clear from the hero's actions. It is not necessary to portray many characters. The center of gravity should be in two persons: him and her." 

Flipping through a notebook from 1999, my last year in grad school, I discovered this passage from Chekhov. The advice strikes me as excellent -- he's Chekhov, after all -- and I only wish I'd paid more attention to it over the past ten years. It's funny how, the more you learn, the more that's left to learn -- and most of it is quite simple, and you knew it all along.