This essay offers an account of Thomas Aquinas’s very complex understanding of love (amor) and related concepts, such as delight (delectatio) and divinely infused charity. It acknowledges the many Platonic influences on Aquinas’s thought in these regards, influences that come to him especially through Augustine of Hippo and Pseudo-Dionysius – both of whom he occasionally criticizes, however, for adhering too closely to Platonic doctrines. Aquinas is intent upon tying all human love in some sense to nature, acknowledging that this entails that in many regards human love is necessitated. To the extent, however, that the rational appetite (the will) is involved, love is not necessitated. The divinely infused virtue of charity brings in further complications, for it is a love that is not natural but comes to a person from above: it is supernatural. And yet it too, according to Aquinas, is not wholly necessitating but affects man in a way that leaves his will free.

Chapter 4 is about the distinction between natural and supernatural virtue. Natural virtues are acquired through human effort and are studied by philosophical ethics. Supernatural virtues must directly come from God. Their existence is known only through revelation. Thomas’s predecessors and most subsequent theologians typically identified these infused or supernatural virtues with the three theological virtues of faith, hope, and charity. Theological virtues are directly about God. But Thomas thinks that there must also be distinct infused moral virtues that exist alongside the acquired moral virtues. These infused virtues are specifically distinct from the acquired moral virtues that share the same matter and from the theological virtues that are about God.