Steve McConnell
It's hard enough to find an error in your code when you're looking for it; it's even harder when you've assumed your code is error-free.
Good code is its own best documentation. As you're about to add a comment, ask yourself, "How can I improve the code so that this comment isn't needed?" Improve the code and then document it to make it even clearer. 
Get it right. Then get it fast.