 Aristotle’s philosophy of nature is re-appropriated in the medieval era, first by Persian and Arabic philosophers such as Avicenna/Ibn Sina (980–1037) and then, with the translation of many of Aristotle’s key texts into Latin, by philosophers in the West, including Thomas Aquinas (1225–1274). In the Latin West, Aristotelian ideas, once introduced, become pervasive throughout the era. In particular, Aristotle’s matter/form conception of substance and his concomitant rejection of atomism become axiomatic points of departure in theorizing about the nature of particular kinds of bodies and the distinctive kinds of processes associated with them. (On Aquinas, see Pasnau 2001 and Stump 2003, Part II; Pasnau 2011 examines in detail a wide range of views of substance in the post-Aquinas scholastic period.)