The City of God, Volume I

Augustine strengthens his case by pointing to twins of different sexes. He personally knows a brother and sister, twins now grown to adulthood, who share a family resemblance yet have pursued completely divergent paths. The brother serves as a military count, constantly abroad on campaign; the sister has never left her native region. More striking still, he is married with numerous children, while she has consecrated herself as a sacred virgin. If the stars at conception were identical for both, they failed to determine even so fundamental a characteristic as sex. Yet astrologers would have us believe that the stars at birth determine the vast difference between the married state and consecrated virginity. Augustine concedes that celestial bodies may influence certain physical phenomena—the seasons, the tides, the growth of certain creatures—but this hardly implies that human wills are subject to stellar domination. The will remains free, and the gifts of God are freely bestowed.

The practice of choosing auspicious days for marriage, planting, or conception further exposes the incoherence of astrological thinking. If the stars truly governed all outcomes, then selecting a favorable day would accomplish nothing, for the natal horoscope would already have determined the result. Yet people believe they can improve their fortunes by choosing the right moment. A learned man, according to one story, selected a specific hour to lie with his wife in hopes of begetting an illustrious son. But if he could alter his destiny through such a choice, then the stars did not fix his destiny after all. The astrologers cannot have it both ways: either the natal chart is supreme and human choice is powerless, or human choice can modify outcomes and astrology is false. Moreover, if the stars rule over all terrestrial things, then one must account for the countless multitudes of plants and animals that come into existence at the same moment yet meet vastly different ends. When a field is sown, innumerable grains germinate simultaneously, yet some are destroyed by disease, some consumed by birds, and some harvested by men. Did each grain have its own distinct constellation? The very suggestion is absurd.

Augustine concludes that the apparent successes of astrologers stem not from any genuine science but from the deceptive influence of malignant spirits, who use such predictions to entangle human minds in falsehood. However, he is willing to accept the term “fate” if it is properly defined—not as the position of the stars, but as the entire chain of causes that depends upon the will of God. In this sense, fate is simply another name for divine providence. The poet Seneca expressed this well when he wrote that the fates lead the willing and drag the unwilling. What he called fate was in fact the will of the supreme Father.

Having disposed of astrological fatalism, Augustine turns to a more sophisticated philosophical challenge: the apparent conflict between divine foreknowledge and human free will. Cicero, seeking to preserve human liberty, had argued that if all future events are foreknown, they must occur by a fixed chain of causes, leaving no room for free choice. Rather than accept this conclusion, Cicero chose to deny divine foreknowledge altogether. Augustine rejects this solution as impious. The religious mind must affirm both truths: that God knows all things before they happen, and that human beings act freely according to their own wills.

The solution lies in recognizing that God’s foreknowledge encompasses human wills as causes. When God foreknows that a person will perform some action, He foreknows it as something the person will do by willing it. The fact that God knew beforehand that someone would will a particular act does not compel that person to will it. Our wills possess genuine power because God created them with power and foreknew how they would be exercised. An order of causes that is certain to God’s foreknowledge does not eliminate the reality of human choice, for human wills themselves occupy a crucial place within that order. Laws, exhortations, rewards, and punishments are not rendered meaningless by divine foreknowledge; rather, God foreknew that these measures would be effective. A person sins not because God foreknew the sin, but because that person wills to sin. If the person had refused to sin, God would have foreknown that refusal instead.

Augustine elaborates on the relationship between necessity and power. Some things happen by necessity—death, for instance, which comes to all regardless of their wishes. But the will is not subject to this kind of compulsion. We do many things that we would not do if we were unwilling; indeed, the very act of willing consists in this, that if we will, it happens, and if we will not, it does not. When we say that it is necessary for God to live forever or to foreknow all things, we do not thereby subject Him to a necessity that diminishes His power. On the contrary, His inability to die or to err is the perfection of His omnipotence. He is called omnipotent because He accomplishes what He wills, not because He suffers what He does not will. Similarly, when we acknowledge that it is necessary for the will to act freely when it acts, we do not subject it to a necessity that destroys liberty. The will exists as will and accomplishes what it does by willing. God foreknew the power He gave to human wills and the use they would make of it; therefore, whatever power they have, they have within certain limits, and whatever they do, they do most assuredly—yet they do it freely.

With these philosophical foundations established, Augustine proceeds to examine the virtues of the ancient Romans and the role of divine providence in granting them empire. God, who holds all kingdoms in His power, chose to bestow dominion upon the Romans as a temporal reward for their relative merits. Though they worshipped false gods, the early Romans possessed qualities worthy of recognition. Their historians record that they were greedy for praise, prodigal of wealth, desirous of glory, and content with modest fortunes. They loved glory so ardently that they were willing to live and die for it. This passion suppressed other desires—avarice, luxury, self-indulgence—and enabled them to achieve great things for their earthly city.

The Roman pursuit of glory manifested first as a love of liberty. Having expelled their kings, they established a republic governed by annually elected consuls. Their historian Sallust observes that the state grew with amazing rapidity once it obtained freedom, so great was the desire for glory that possessed it. This desire drove them to seek not merely liberty but domination. The poet Virgil captures this ambition when he has Jupiter predict that Rome’s sons would reign over Greece and humble proud nations. The Romans developed distinctive arts: the arts of ruling, commanding, subjugating, and vanquishing. They exercised these skills more effectively because they restrained their appetites for pleasure and wealth.