According to Aristotle in De Anima 2.12, perception occurs when a perceiver receives a perceptible form without its matter. The result is that a percipient is qualitatively altered in a way by its reception of the perceptible form. Typically, instances are qualitative alteration as classified by Aristotle as kinetic changes from contrary to contrary. What I argue from De Anima 2.5 is that perceptual alterations are of the atypical variety and are classifiable as instances of metabolic change from contradictory to contradictory, namely as instances of qualitative generation. This qualitative generation view, I argue, is not just consonant with what Aristotle says in Physics 7.3 about the limitations of alteration based on his four-fold division of the species of the category of quality in Categories 8, but also with his views on metabolic and kinetic change in Physics 3.1-3 and 5.1-2, alteration in Generation and Corruption 1.7, and Aristotle’s application of his metabolic doctrines to perception in De Anima 3.2. Moreover, as I argue, this view comes with the support of several of the ancient commentators on Aristotle, such as Alexander of Aphrodisias, John Philoponus, and Simplicius of Cilicia. The result is an interpretation of Aristotle’s theory of perception which leans decidedly in the direction of Myles Burnyeat’s spiritualism rather than Richard Sorabji’s literalism, yet without sanctioning the former. Noteworthy features of this work are a detailed and innovative treatment of the metabolic status of the four species of quality with respect to contrariety, a new soft-relative account of quantitative generation in Physics 7.3, and a realist reading of De Anima 3.2, which draws heavily on Aristotle’s single actuality account of agency and patiency in change from Physics 3.3.