Book excerpt: In Computing for Ordinary Mortals, cognitive scientist and AI expert Robert St. Amant explains what he calls, "the really interesting part" of computing, which are the ideas behind the technology. They're powerful ideas, and the foundations for everything that computers do, but they are little discussed. This book will not tell you how to use your computer, but it will give you a conceptual tour of how it works. Some of the ideas, like modularity which are so embedded in what we do as humans, can also give us insight into our own daily activities, how we interact with other people, and in some cases even what's going on in our heads. Computing is all around us, and, to quote Richard Hamming, the influential mathematician and computer scientist, "The purpose of computing is insight, not numbers," and it is this insight that informs the entire book.