In its heyday, sentence diagramming was de rigueur in grammar schools across the country. Veteran copy editor Kitty Burns Florey learned the method in sixth grade from Sister Bernadette: "It was a bit like art, a bit like mathematics. It was a picture of language." In this offbeat history, she explores the sentence-diagramming phenomenon, as well as what the diagrams of famous writers' sentences reveal about them. Was Mark Twain or James Fenimore Cooper the better grammarian? Can the ability to diagram a sentence improve your life? And what about Gertrude Stein?