 The sciences, for Ibn Rushd, fundamentally divide into the theoretical (naẓarīya), which is aimed at knowledge (ʿilm), and the practical (ʿamalīya), which is concerned with voluntary action (Republic I.21; LongPhys proem). The chief practical science is politics, which Ibn Rushd sees as dividing, much like medicine, into a more theoretical and a more practical part. The first and more theoretical part examines voluntary actions in general, their associated dispositions (the virtues and vices), and the relationships between these elements. The second, more practical part examines how these dispositions become established within souls and how they are perfected and impeded (Republic I.21). The first part is found in Aristotle’s Nicomachean Ethics, and the second part in his Politics. Although Ibn Rushd composed a commentary on the first of these, and although he knew the second was available in Arabic elsewhere, he complains that it “has not yet reached us on this peninsula” (ParaEthics X.160G). Accordingly, he chose to comment on Plato’s Republic as an alternative source for the second part of political science.