In this paper I first address what I consider a central issue in the account of perception in Plato’s Timaeus, namely, how the pathemata pass through the body to reach the soul, and thus become aistheseis. My point in Section 1 is that in tackling this issue Plato aims to provide a firm physiological basis to the notion of perception that starts to emerge in the Theaetetus and the Philebus and is crucial to the late development of his theory of (...) cognition. In the ensuing section I try to put the account of perception in the Timaeus into a historical perspective, aiming to highlight two points: a) Plato’s description of the way in which sensible impressions “travel” inside the body and interact with its parts and other constituents is largely indebted to previous theories, such as those we find, for example, in Empedocles and a few Hippocratic writers; b) The leading role in this story (where internal air plays a significant supporting role) is played by blood flowing through the vascular system and thus performing a crucial cognitive function. Moreover, emphasizing the role of blood as well as analyzing the elaborate way in which perceptions are transmitted through the body to the soul proves vital to appreciate (in Section 3) the cognitive status of the lower parts of the soul (which are more involved in perception) and their relation to reason. Overall, the paper adds further elements to our understanding of Plato’s embodied approach to cognition. I had already written (and submitted) this article when Johansen (2021) was published. The latter’s approach to the role of blood in Plato’s physiology of knowledge in the Timaeus converges in part with mine (as I was pleased to find out), partly due to our overlapping sources and bibliography. (shrink)