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)

The principles governing elemental composition, variation, and change in Plato’s Timaeus appear to be incompatible, which has led commentators to prioritize some of the principles to the exclusion of others. Call this seeming incompatibility the problem of isomorphic variants. In this paper, I develop the theory of proportionate atomism as a solution to this problem. Proportionate atomism retains the advantages of rival interpretations but allows the principles of material composition, variation, and change to combine into an internally coherent and explanatorily (...) powerful atomic physics. (shrink)