Don't bite my finger, look where I am pointing. - Warren Sturgis McCulloch

This book is not for the engineer content with hardware, nor for the biologist uneasy outside his specialty; for it depicts that miscegenation of Art and Science which begets inanimate objects that behave like living systems. They regulate themselves and survive: They adapt and they compute: They invent. They co-operate and they compete. Naturally they evolve rapidly.
Pure mathematics, being mere tautology, and pure physics, being mere fact, could not have engendered them; for creatures to live, must sense the useful and the good; and engines to run must have energy available as work : and both, to endure, must regulate themselves. So it is to Thermodynamics and to its brother Σp log p, called Information Theory, that we look for the distinctions between work and energy and between signal and noise.
For like cause we look to reflexology and its brother feedback, christened Multiple Closed Loop Servo Theory, for mechanical explanation of Entelechy in Homeostasis and in appetition. This is that governance, whether in living creatures and their societies or in our living artefacts, that is now called Cybernetics.

With all of these limitations and hazards well in mind, let us ask whether a knower so conceived is capable of constructing the physics of the world which includes himself. But, in so doing, let us be perfectly frank to admit that causality is a superstition.

I met Walter Pitts, then in his teens, who promptly set me right in matters of theory. It is to him that I am principally indebted for all subsequent success. He remains my best adviser and sharpest critic. You shall never publish this until it passes through his hands.