The best book on writing I've ever read. This book lightly touches on grammar, only to get it out of the way, and then is on to the act of writing. He focuses on the thought process of writing, what to write about, how to write about different subjects, and most importantly how to rewrite what you've just written. Everybody that writes, anything, should read the first section, titled "Principles". Those first fifty pages apply to all forms of writing and will serve you well. William Zinsser wrote in such an engaging style that I'll be adding at least two more of his books to my reading list. And because he talked about it so fondly I might even reread Walden, but that's a long shot.