 In the Metaphysics, Aristotle praises Archytas for having offered definitions which took account of both form and matter (1043a14–26 = A22). The examples given are “windlessness” (nênemia), which is defined as “stillness [the form] in a quantity of air [the matter],” and “calm-on-the-ocean” (galênê), which is defined as “levelness [the form] of sea [the matter].” The terms form and matter are Aristotle’s, and we cannot be sure how Archytas conceptualized the two parts of his definitions. A plausible suggestion is that he followed his predecessor Philolaus in adopting limiters and unlimiteds as his basic metaphysical principles and that he saw his definitions as combinations of limiters, such as levelness and stillness, with unlimiteds, such as air and sea. The oddity of “windlessness” and “calm-on-the-sea” as examples suggests that they were not the by-products of some other sort of investigation, e.g. cosmology, but were chosen precisely to illustrate principles of definition. Archytas may thus have devoted a treatise to the topic. Aristotle elsewhere comments on the use of proportion in developing definitions and uses these same examples (Top. 108a7). The ability to recognize likeness in things of different genera is said to be the key. “Windlessness” and “calm-on-the-ocean” are recognized as alike, and this likeness can be expressed in the following proportion: as nênemia is to the air so galênê is to the sea. It is tempting to suppose that Archytas, who saw the world as explicable in terms of number and proportion, also saw proportion as the key in developing definitions. This would explain another reference to Archytas in Aristotle. At Rhetoric 1412a9–17 (= A12) Aristotle praises Archytas precisely for his ability to see similarity, even in things which differ greatly, and gives as an example Archytas’ assertion that an arbitrator and an altar are the same. DK oddly include this text among the testimonia for Archytas’ life, but it clearly is part of Archytas’ work on definition. The definitions of both an altar and an arbitrator will appeal to their common functions as a refuge, while recognizing the different context and way in which this function is carried out. For doubts about this reconstruction of Archytas’ theory of definition, see Barker 2006, 314–318 and Schofield 2014, 80.