We understand Aristotle’s soul–body hylomorphism better if we first understand the critical discussions of his predecessors which occupy most of the first book of his De Anima.  Given that he regards his view as preferable to all earlier approaches, he must also think that his alternative, hylomorphism, avoids the pitfalls he identifies in those positions. In some cases, it is easy to see why he might think hylomorphism is defensible where they are not: for instance, he regards the reductively materialistic views of the earliest natural philosophers as explanatorily impoverished. In other cases, however, this is far from clear. Aristotle highlights for special consideration the view that the soul is a harmonia (attunement) of the body, a view which, as was noted in antiquity, bears more than a passing resemblance to his own hylomorphism. It proves both difficult and instructive to determine, then, how he supposes hylomorphism avoids the problems he identifies in the doctrine of the soul as a harmonia. The core difference, it emerges, turns on Aristotle’s thoroughgoing teleology: the soul, he thinks, unlike a harmonia, has an intrinsic good toward which the body is orchestrated.