BODIES ARE ACTIVE ONLY BY MEANS OF INCORPOREAL POWERS.
(9.) There are men who locate the soul in the body, so as to give her a foundation in some sphere of activity, to account for the various phenomena in the body, such as getting hot or cold, pushing on or stopping, (and the like). They evidently do not realize that bodies produce these effects only through incorporeal powers, and that those are not the powers that we attribute to the soul, which are thought, sensation, reasoning, desire, judiciousness, propriety and wisdom, all of them entities that cannot possible be attributes of a corporeal entity. Consequently, those (materialists) attribute to the body all the faculties of incorporeal essences, and leave nothing for the latter.
WHY BODIES ARE ACTIVATED BY INCORPOREAL POWERS.
The proof that bodies are activated only by incorporeal faculties may be proved as follows: Quantity and quality are two different things. Every body has a quantity, but not always a quality, as in the case of matter, (according to the Stoic definition, that it was a body without quality, but possessing magnitude — Eneada-II, 4, 1). Granting this, (you Stoic) will also be forced to admit that as quality is something different from quantity, it must consequently be different from the body. Since then every body has a quantity, how could quality, which is no quantity, be a body? Besides, as we said above (Guthrie-Ennead-IV, 7, 5), every body and mass is altered by division; nevertheless, when a body is cut into pieces, every part preserves the entire quality without undergoing alteration. For instance, every molecule of honey, possesses the quality of sweetness as much as all the molecules taken together; consequently that sweetness cannot be corporeal; and other qualities must be in a similar case. Moreover, if the active powers were corporeal, they would have to have a material mass proportional to their strength or weakness. Now there are great masses that have little force, and small ones that have great force; demonstrating that power does not depend on extension, and should be attributed to some (substance) without extension. Finally, you may say that matter is identical with body, and produces different beings only by receiving different qualities (the Stoics considering that even the divinity was no more than modified matter, their two principles being matter and quality (Eneada-II, 4, 1); the latter, however, was also considered as body). How do you (Stoics) not see that qualities thus added to matter are reasons, that are primary and immaterial? Do not object that when the spirit (breath) and blood abandon animals, they cease to live; for if these things are necessary to life, there are for our life many other necessities, even during the presence of the soul (as thought Nemesius).