  Characteristic of human souls, or human beings, are the intellective and motive powers, that is to say, the intellect and will. William thinks that of these, the will is by far the more noble power, and he is accordingly puzzled by the fact that neither Aristotle nor Avicenna have much to say about it. These authors do, however, discuss the intellective power at great length, and William accordingly devotes considerable attention to combating errors he sees in their teachings on the intellect.