In the fifth part of the Discourse, a few pages are devoted to the thesis that was to become notorious as the doctrine of the bête-machine, the doctrine that all animate bodies are machines, and, in particular, that all non-human animate bodies are only machines (A.T. VI, pp. 40–60, esp. pp. 57–59).¹ In looking back to consider the impact on modern thought of the Cartesian revolution, this seems a minor and peripheral theme, no more weighty (except to animal lovers) than the pages it occupies in proportion to the whole volume published in 1637 (A.T. VI, pp. 1–485). Yet if we start from this document and put it, along with other texts allied to it, into the framework of the Cartesian enterprise as a whole, it turns out, I think, to guide us to some fresh insights — and also, I confess, to some fresh problems. I want to consider the implications of animal automatism, then, in four contexts: first, as one of the two allegedly objectionable features of Cartesian natural philosophy, which Descartes's disciples felt called on to defend; second, as an aspect of the Cartesian effort to reduce all natural change to local motion; third, in the context of Descartes's interest in automata; and fourth, closely related to the third, in the context of Descartes's defense of his new program as related to what he calls (with a capital M) Mechanica.