But this very fact that it is a deficient being is accidental to good to which of itself it belongs to act. Now, a good will does not produce a morally bad act, since it is from the good will itself that a moral act is judged to be good. Hence evil never follows in the effect, unless some other evil pre-exists in the agent or in the matter, as was said above. But in voluntary things the defect of the action comes from the will actually deficient, inasmuch as it does not actually subject itself to its proper rule. This defect, however, is not a fault, but fault follows upon it from the fact that the will acts with this defect.
Evil has no direct cause, but only an accidental cause, as was said above.
I am the Lord, and there is no other God, forming the light, and creating darkness, making peace, and creating evil. Further, the effect of the secondary cause is reduced to the first cause. But God is the cause of the safety of all things. Therefore He is the cause of all perdition and of all evil. Hence, the evil which consists in defect of action, or which is caused by defect of the agent, is not reduced to God as to its cause.