The quote is a joke, Will. If you don't comment your code, others will have an impossible time understanding what it does. Also, it gets tiring trying to remember what significance FLAG2 has in your function after you've been absent from your code for a while.

Personally I've made it a habit to make a comment every time I do anything significant. If I turn on FLAG2, I make a comment. If I manipulate a vector with the "vec_" functions, I make a comment. Generally you should make comments that streamline the steps the computer should be going through in your function, such that if you read nothing but the comments in your function it should be clear what you're trying to accomplish.