Father Pegues discusses St. Thomas Aquinas’ teaching on man’s primordial state. St. Thomas treats of this at length in his Treatise on Man (Summa Theologica I, 75-102).
God created man in a state of great perfection: (1) his mind possessed knowledge free from error; (2) he was in a state of original justice, having all the virtues of mind and will; and (3) his soul had command over his body and over every creature inferior to man. “Since original justice and the gifts of integrity and complete moral rectitude are inseparable from human nature as such these would have been transmitted to all by way of origin or generation had not sin stood in the way.”
Man was not created in a state of final and perfect happiness. Rather, his happiness on earth was temporary. One might call this “a state of initial happiness which was to prepare man by way of merit to enter into the state of his final and perfect happiness. . . . He would have acquired this happiness in the glory of heaven in the company of the angels, whither God would have transferred him after a certain period of probation.”
“Man is a composite of spirit and body, in whom the world of spirits and the world of bodies in some sort coalesce.” His spirit is his soul. “The soul of a plant has only vegetative life, the soul of an animal has both vegetative and sensitive life, whereas the soul of man has in addition an intellective life.” This intellective life distinguishes man from all other earthly creatures. The intellective life of the human soul is independent of the body because “the object of thought is something wholly immaterial.” Moreover, “if the soul itself were not wholly immaterial it could not attain by thought to an object wholly immaterial.”
The three vegetative powers of the human soul give life to the body. These are nutrition, growth, and reproduction. The sensitive powers of the soul are of two types: knowing and loving. One way of knowing is through the five external senses, by which a person communicates with the physical world. These are seeing, hearing, smelling, tasting, and touching. Another way of knowing is through the four internal sensitive powers, which bridge the gap between the external senses and the intellect. These are the common (or central) sense, the imagination, instinct (or estimative sense), and memory. Yet another way of knowing—and this is man’s highest power—is through his reason (or intellect).
The powers of loving incline a person to seek what his powers of knowing present as good, and to turn away from what his powers of knowing present as evil. One power of loving is called “the heart” or “the affections”; the other, which is more perfect, is the will.
Quotations from Thomas Pegues, Catechism of the “Summa Theologica” of Saint Thomas Aquinas, trans. Aelred Whitacre (New York: Benziger, 1922).