Summa contra Gentiles3.11 Chapter XI. That the subject of evil is a good

From what we have said it can be shown that every evil is seated in some good.

For evil cannot exist by itself: since it has no essence, as was proved above.’ Therefore evil needs to be in some subject. Now every subject, as it is a substance, is a good, as is evident from what has been said.” Therefore every evil is in a good.

Also. Evil is a privation, as we have shown.? Now privation and the lacking form are in the same subject. But the subject of a form is a being in potentiality to that in the same genus. Therefore privation, that is an evil, is in some good as its subject.

Moreover. A thing 1s called evil because it hurts: nor otherwise than because it hurts a good: for it is good to hurt evil, since the corruption of evil is good. Now it would not hurt a good formally, unless it were in that good: thus blindness is hurtful to a man forasmuch as it is in him, Therefore evil must be in a good.

Again. Evil is not caused except by good, and then only accidentally. Now whatever is accidental is reducible to that which is per se. Consequently together with the evil effect that is caused accidentally by a good, there must be some good which is the per se effect of that good, so as to be the foundation of that evil: because what is accidental is founded on what is per se.

Seeing, however, that good and evil are mutually opposed; and that one of two opposites cannot be the subject of the other, but expels it: someone at a cursory glance might think it unreasonable to state that good is the subject of evil.

And yet it is not unreasonable if the truth be sought thoroughly. For good, even as being, is predicated univer- sally: since every being, as such, is good, as we have shown." Now it is not unreasonable that non-being should have being for its subject: because every privation is a non-being, and yet its subject is a substance, which is a being. But non-being is not in an opposite being as its subject: for blindness is not universal non-being, but a particular kind of non-being, namely privation of sight: therefore it is not in sight, as its subject, but in an animal. In like manner evil has for its subject, not the opposite good;—for it is the privation of this good,—but some other good: thus moral evil is in a natural good; and an evil of nature, to wit priva- tion of a form, is in matter, which is a good as a being in potentiality.