Chapter 30

In this same way the pagan philosophers stated the difference between substance, and nature, by saying that substance was being in the strict sense, whereas nature was substance which had been made specific by essential differences so as to have, in addition to being in the strict sense, being in such a way, whether rational or irrational, mortal or immortal. In other words, we may say that, according to them, nature is that unchangeable and immutable principle and cause and virtue which has been implanted by the Creator in each species for its activity—in the angels, for thinking and for c