The last word in this sentence is a four letter noun.

I'm lazily sneaking this in from the end of Round Two, and because it's now Round Three, I won't say much, other than if you are at all interested in shifting your perception and thinking about the world (and life and mathematics and the self and the way in which your mind works) in a Completely new light, please please please read this book. Because, after all, haven't you ever caught yourself wondering what I is?