Aristotle's explanation of the “active intellect” inDe AnimaIII, 5 constitutes a problem for us simply because we have to take this philosopher so seriously. If he were a writer given to poetic lapses or mythical adornments to his work we could consider dismissing the whole chapter as unessential. However, we know that Aristotle does not write unessential chapters, and that he is invariably engaged in an attempt to explain his subject fully and systematically, neither adding to it nor leaving anything (...) out.TheDe Anima, for example, is an attempt to describe the characteristics of living things, in an ascending order from the basic functions of vegetables to the most abstract thinking by human beings. The activities of nutrition, sensation, common sense, imagination, and movement are presented in Book II and in the early part of Book III. (shrink)