Near the end of his speech, Timaeus outlines a theory of bodily health and disease which has seemed to many commentators loosely unified or even inconsistent . But this section is better unified than it has appeared, and gives us at least one important insight into the workings of physical causality in the Timaeus. I argue first that the apparent disorder in Timaeus’s theory of disease is likely a deliberate effect planned by the author. Second, the taxonomy of disease in (...) the passage consists of one genus subsuming two species. Third, in Timaeus’s theory, health lies between perfect stability and a chaos of all possible motions; this indicates a conception of health as the activation of the body's powers in the right way. A power is a property directed towards bringing about some change. Fourth, the activation of these powers can change depending on the location of their possessors. This last point shows that causation among the physical items in the Timaeus involves structures as well as pushes. (shrink)

Scholarship on Plato's Timaeus has paid relatively little attention to Tim. 77a–81, a seemingly disjointed passage on topics including plants, respiration, blood circulation, and musical sounds. Despite this comparative neglect, commentators both ancient and modern have levelled a number of serious charges against Timaeus' remarks in the passage, questioning the coherence and explanatory power of what they take to be a theory of respiration. In this paper, I argue that the project of 77a–81e is not to sketch theories of respiration, (...) circulation, and digestion, but to explain how the human body is maintained in light of and despite constant environmental depletion. Further, I argue that in order to understand this account of “the replenishing system,” we need to understand Timaeus' striking analogy of the fish trap or nassa. Commentators have generally focused directly on the workings of the bodily construction that Timaeus likens to a fish trap, but without considering how we should understand the analogy qua analogy. I develop a functional reading of the analogy that yields a coherent account of the replenishing system on which previous criticisms of Timaeus' remarks on respiration do not arise. Aside from lending greater unity to the passage, both internally and within its immediate context in the dialogue, this account of the replenishing system contributes to our understanding of Timaeus' reason-and-necessity explanatory framework as applied to the human body and has noteworthy implications for specific explanatory principles, in particular like-to-like motion and circular thrust. (shrink)