Thomas Aquinas

“ Now we must consider that God is the universal cause of the enlightening of souls, according to Jn. 1:9: "That was the true light which enlighteneth every man that cometh into this world," even as the sun is the universal cause of the enlightening of bodies, though not in the same way; for the sun enlightens by necessity of nature, whereas God works freely, through the order of His wisdom. ”

“ On the other hand, God, of His own accord, withholds His grace from those in whom He finds an obstacle: so that the cause of grace being withheld is not only the man who raises an obstacle to grace; but God, Who, of His own accord, withholds His grace. In this way, God is the cause of spiritual blindness, deafness of ear, and hardness of heart. ”

“ The effect which proceeds from the middle cause, according as it is subordinate to the first cause, is reduced to that first cause; but if it proceed from the middle cause, according as it goes outside the order of the first cause, it is not reduced to that first cause: thus if a servant do anything contrary to his master's orders, it is not ascribed to the master as though he were the cause thereof. In like manner sin, which the free-will commits against the commandment of God, is not attributed to God as being its cause. ”