In ii 2 Aristotle has explored the cause of mortal life through investigating the various powers of soul and how they might or might not be separate from each other. His main concern was that the other powers not be separate from the nutritive life power. Now he considers more fully how the powers of soul are distributed to living things and why they unite in the soul. Previously he was arguing against multiple souls in the ensouled being, while now he argues that each kind of living being has a unified soul. If the powers of soul are in succession, then nutritive capacity ushers in life with possibilities for further sorts of life. The powers (δυνάμεις) of soul referred to are nutritive power (θρεπτικόν), perceptive (αἰσθητικόν), desiderative (ὀρεκτικόν), motive according to place (κινητικὸν κατὰ τόπον), intellective (διανοητικόν, 414a29–32). Different classes of mortal living things possess all, some, or one of these (cf. 413b32–33). Because he is considering how widely these faculties extend and which can be separate, he here lists them, unusually, in the order of decreasing extensiveness. Humans have all of these functions, some animals only some, and plants just the nutritive capacity. As more capabilities are added, the number of living things possessing them decreases. Aristotle reconsiders how these functional capacities separate and combine in the classes of mortal living beings to guarantee that he has dealt well with all the powers of mortal living things and that his definition of soul covers all the soul's powers.