/summa/FP/FPV/FP_Q47:
After considering the production of creatures, we come to the consideration of the distinction of things. This consideration will be threefold---first, of the distinction of things in general; secondly, of the distinction of good and evil; thirdly, of the distinction of the spiritual and corporeal creature.
Under the first head, there are three points of inquiry:
(1) The multitude or distinction of things.
(2) Their inequality.
(3) The unity of the world.