Exodus — Chapter 7

I will harden the heart of Pharaoh. Lapide addresses the classic theological problem: is God the author of Pharaoh's hardness? He follows Augustine and Aquinas: God hardens Pharaoh not by infusing any evil, but by withdrawing His softening grace (subtrahere gratiam emollitivam). This withdrawal is perfectly just because Pharaoh had previously hardened his own heart by free choice. The hardening of Pharaoh is therefore both his own act and God's judgment—a punitive hardening (induratio poenalis) following on culpable resistance.

Aaron cast down his rod before Pharaoh and it became a serpent; the Egyptian magicians did likewise, but Aaron's rod swallowed their rods. Lapide discusses whether the magicians performed genuine miracles. He concludes with Augustine and Aquinas that they produced real, though limited, effects by the power of demons—but demons can only work with created matter; they cannot create ex nihilo. The swallowing of their serpents by Aaron's rod signifies the superiority of divine power over demonic art and prefigures Christ's conquest of the devil.

In this thou shalt know that I am the Lord: behold, I will strike with the rod that is in my hand the water of the river, and it shall be turned into blood. The first plague—water turned to blood—is a judgment against the Egyptian worship of the Nile as a god (Hapi). Lapide notes this pattern in all ten plagues: each strikes an element of Egyptian religion. God punishes idolatry through the very objects worshipped. He applies this morally: the creature that is loved inordinately becomes the instrument of punishment for those who set it in God's place.