Man a Machine

A short, provocative essay, published anonymously in Leiden, that extends Descartes' account of animals as machines to human beings and drops the immaterial soul altogether. La Mettrie, a physician, argues from medicine rather than metaphysics. The states of the mind follow the states of the body: illness, fever, sleep, food, drink, opium and coffee all change thought and character, and differences in the brain track differences in intelligence between humans and other animals. Comparative anatomy suggests a difference only of degree, and he speculates that an ape might be taught to speak. Muscles that twitch after death and hearts that keep beating after removal show that organised matter has its own power of motion. The body is a machine that winds its own springs, and 'soul' is simply a name for the part of us that thinks. Morality survives as a natural feeling, and he claims the materialist will live more humanely. The book caused a scandal even in tolerant Holland.

It is one of the boldest early statements of materialism about the mind, and its medical evidence anticipates today's arguments from brain science.