The purpose of this book is to explain computer models designed to simulate how the human mind perceives music. The models are heavily based on Lerdahl and Jackendoff's work with preference rules, and may be seen as a test application of that work. Yet designing a computer program that comes to the same result as the human mind is not the same as discovering the process by which the human arrives at that result. That is where the book is highly speculative. Not enough allowance is made for cultural differences in the way music is perceived, nor for the influence bodily experience of music has on its perception which must of necessity be missing from a computer model. Still, the book is an interesting read for the questions it raises, and for the possibilities it puts forth.