Motion and Mutation

Motion is the Intellakia of that which is in capacity, so far as it is in capacity. A thing then happens to be moved when this energy exists, and neither prior nor posterior to it is manifest. Everything is able at one time to energize and at another not - building is a certain motion. The cause why motion appears to be indefinite is because it can neither be simply referred to the capacity, nor to the energy of beings. For no one of them is this particular thing, nor of a particular quality, nor does it belong to any of the other categories. Neither is mutation into these, nor from these, rather than from their opposites.