Aristotle's treatment of the deliberative imagination is mentioned only very briefly in the course of his treatment of local motion. “The soul of animals,” says Aristotle, “is characterized by two faculties, the faculty of discrimination which is the work of thought and sense, and the faculty of originating local movement.” Having dealt with the former earlier in De Anima, Aristotle sets out to investigate the latter.
The first problem that presents itself is whether the originator of motion in an animal is a part of the soul or the whole soul. Given his earlier treatment of motion, it is evident that one part must be immovable and the other moved. Therefore the originator of movement is not the whole soul. But if the originator is a part of the soul, a difficulty arises--what are the parts of the soul? Different thinkers divide the soul differently, and different divisions may be made under differing aspects.