In my paper I propose a new interpretation of a notoriously difficult passage from the Pseudo-Hippocratic treatise De victu, which deals with the activities of the soul during sleep. The passage in question has been interpreted by many scholars as a kind of Orphico-Pythagorean journey of the soul, and thus as key evidence for body-soul dualism in De victu. However, as I attempt to demonstrate, the soul does indeed take a journey, but not a Pythagorean one: in my reading of the text, it travels from the periphery deeper inside the body, to a place the author calls the “oikos of the soul”. I argue that this oikos best correspondsto a kind of ‘cognitive center’, located in the chest and/or heart-region. This type of soul-journey points not to a dualist but to a materialist interpretation of De victu’s psychology. Further, I argue that overall the treatise is closer to the materialist psychophysiology of such fifth century Presocratics as Diogenes of Apollonia.