Happy b'day to the best writing book ever made, Strunk & White's The Elements of Style. Not my favorite writing book (On Writing by Stephen King or Of Cunning and Craft by Peter Selgin are my favs), but easily the most important, followed by William Zinsser's On Writing Well.
First published in 1959, the classic book truly gets at what people know, at least as it teaches us the importance of clarity and grace in writing.
A perfect book? Not even close, but easily the most important book on writing every published, with Zinsser's excellent book not so far behind.