Why Did Adam Originally Need Grace?

Creation of Adam
Michelangelo (Sistine Chapel, 1510)

Aquinas answers this question in Summa Theologica I Q.95 a.1 co.. He explains that man was made by God in such a way that man's reason was subject to God, his lower powers were perfectly subject to his reason, and his body also was perfectly subject to his soul. But the first subjection was the cause of the latter two subjections. Then Aquinas says,

"Now it is clear that such a subjection of the body to the soul and of the lower powers to reason, was not from nature; otherwise it would have remained after sin; since even in the demons the natural gifts remained after sin, as Dionysius declared (Div. Nom. iv). Hence it is clear that also the primitive subjection by virtue of which reason was subject to God, was not a merely natural gift, but a supernatural endowment of grace; for it is not possible that the effect should be of greater efficiency than the cause. Hence Augustine says (De Civ. Dei xiii, 13) that, "as soon as they disobeyed the Divine command, and forfeited Divine grace, they were ashamed of their nakedness, for they felt the impulse of disobedience in the flesh, as though it were a punishment corresponding to their own disobedience." Hence if the loss of grace dissolved the obedience of the flesh to the soul, we may gather that the inferior powers were subjected to the soul through grace existing therein."

Here is Aquinas's argument. The subjection of Adam's body to his soul and of the lower powers to his reason was an effect of the subjection of his reason to God. But it is not possible that the effect should exceed the cause. And since the subjection of the body to the soul and of the lower powers to reason was not from nature [for otherwise these two subjections would have remained after Adam's sin], it follows that the subjection of Adam's reason to God was also not a merely natural gift but was a supernatural endowment of grace. And the quotation from Augustine confirms this. Hence Aquinas concludes that if the loss of grace dissolved the obedience of the flesh to the soul, the inferior powers must have been subject to the soul through grace existing in them.

According to Aquinas it is not that Adam was naturally disordered, but that his nature alone did not preserve his order in his original state. Nor is Aquinas saying that Adam initially had some defect. The need for grace in the initial state is not based on matter, for even the angels, as beings having no matter, needed grace in their original state. Aquinas, along with the Church, believed that everything God made was very good, and that Adam was created posse non pecarre (with the ability to avoid sinning). Nor is Aquinas saying that the image of God in man was a superadded gift. Man bears the image of God through the rational power that is natural to man.

For Aquinas, grace is not merely divine favor; it was something in Adam and Eve. Aquinas would have treated the notion that grace is either something ontological or merely divine favor, as a false dilemma. He teaches in Summa Theologica I-II Q.110 a.1 that grace has three aspects. In one sense it refers to favor. In another sense it refers to the gift given as an expression of that favor. And in another sense it refers to the gratitude one has for the reception of a gratuitous gift. So we don't have to choose between grace as divine favor, and grace as divine gift.

The gift of grace that God gave to Adam and Eve was not a substance, but a quality inhering within their souls. (ST I-II Q.110 a.2) God "infuses" (infundit) into us "certain forms or supernatural qualities (aliquas formas seu qualitates supernaturales), whereby we may be moved by Him sweetly and promptly to acquire eternal good." The Catholic Catechism teaches that Adam and Eve were created having the grace of original holiness and justice (CCC 375), by which they were in harmony with God, and thus had an inner harmony within themselves (no concupiscence), a harmony between each other, and a harmony with all of creation. This entire harmony was lost when they disobeyed God.