This text of Bonaventure’s gives a nice indication of how Aristotle begins to influence the debate about the relation between the soul and its powers in the Latin West around the 1250s. In this text, Bonaventure is still very much in dialogue with the earlier debate. He recounts the early twelfth-century identity theory and earlier versions of the distinction theory, and he argues in favor of the version of the distinction theory defended by early Franciscans like Alexander of Hales. As Bonaventure states this latter theory, the soul and its powers are one “in substance” but differ “in essence”, the essential difference having to do with the fact that the powers of the soul, unlike the soul itself, are relations. But Bonaventure also introduces a philosophical innovation into this theory—one that draws on Aristotle. He argues that the powers of the soul, despite being relations, are special types of substances, namely, substances “by a tracing back” (per reductionem). He understands by “substances by a tracing back” imperfect occupants of the category of substance.