Exploring the systematic connections between Aristotle’s theory and practice of science has emerged as an important concern in recent years. On the one hand, we can invoke the theory of the Posterior Analytics to motivate specific moves that Aristotle makes in the course of his actual investigation of the natural world. On the other, we can use Aristotle’s practice of science to illuminate the theory of the Posterior Analytics, which is presented in a notoriously abstract, and at times also elliptical, (...) way. I would like to contribute to this interpretative tradition with a study of how Aristotle explains the phenomenon of sleep and waking. (shrink)