Proclus argues in De Subsistentia Malorum §5 for a "most paradoxical" conclusion, that "one and the same reason preserves for us the perfection of the whole world and posits evil within beings; on account of which evil does not only exist for the sake of the good, but evil is itself good." By comparing this abstract argument with material from the Timaeus and Alcibiadescommentaries, I show that what Proclus has in mind is that for the sake of the perfection of the world, irrational animal species have to exist and that the only means for their coming to be is by humans consistently leading irrational, i.e. evil, lives, such that after their deaths, their immortal minds go on to animate irrational animals. The necessity of irrationality is dependent solely on the divine plan of assimilating the natural world to its divine archetype, not being required either by a pre-existent evil matter or mind. Nor is the animation of irrational animals simply a scheme to make the best out of human evils: our immortal minds are per se rational and left to themselves would not lead irrational lives. Confirming the divine origins of irrationality for Proclus, he appears also to posit a divine cause for human irrationality, "Circe", which I argue must act as a "divine sophist", setting up a web of deceptive appearances to seduce inherently rational minds into leading irrational lives. This is in line with what we know about late Platonic interpretations of Plato's Sophist, which took it to be a dialogue about the natural world and specifically about the ordering of the Earth and its atmosphere (i.e. the region below the Moon) by the gods.