Summa contra Gentiles3.15 Chapter XV. That there is no sovereign evil

It follows from this that there cannot be a sovereign evil, that is the principle of all evils.

For a sovereign evil must needs exclude the association of all good: just as the sovereign good is that which is wholly disconnected from all evil. Now there cannot be an evil entirely apart from good: for it has been proved that evil is seated in some good.! Therefore nothing is supremely evil.

Again. If anything be supremely evil, it must be essentially evil: even as the supreme good is that which is essentially good. But this is impossible: since evil has no essence, as was shown above.” Therefore it is impossible to suppose a supreme evil that is the principle of evils. Also. That which is a first principle is not caused by anything. Now every evil is caused by a good, as we have proved.? Therefore evil is not a first principle.

Further. Evil does not act except by virtue of a good; as we have proved. But a first principle acts by its own virtue. Therefore evil cannot be a first principle.

Moreover. Since that which is accidental is subsequent to that which is per se, the accidental cannot be first. Now evil does not occur except accidentally and unintentionally, as we have proved. Therefore evil cannot be a first principle.

Again. Every evil has an accidental cause, as we have shown.’ But a first principle has no cause, either per se, or accidental. Therefore evil cannot be the first cause in any genus.

Furthermore. A per se cause precedes one that is accidental. But evilis none but an accidental cause, as we have proved. Therefore evil cannot be a first principle.

Hereby is refuted the error of the Manichees, who maintained the existence of a sovereign evil, that is the first principle of all evils.