"The same process of reasoning enables us to perceive that, without prejudice to divine providence, evil can arise in the world because of defects in secondary causes. Thus in causes that follow one another in order, we see that evil finds its way into an effect owing to some fault in a secondary cause, although this fault is by no means the product of the first cause. For example, the evil of lameness is caused by a curvature in the leg, not by the motive power of the soul. Whatever movement there is in the progress of a lame man, is attributed to the motive power as to its cause; but the unevenness of the progress is caused by the curvature of the leg, not by the motive power. Similarly the evil that arises in things, so far as it has existence or species or a certain nature, is referred to God as to its cause; for there can be no evil unless it resides in something good,. as is clear from what we said above. But with regard to the defect that disfigures it, the evil is referred to a lower, defectible cause. Accordingly’ although God is the universal cause of all things, He is not the cause of evil as evil. But whatever good is bound up with the evil, has God as its cause."