The City of God stands as Augustine's masterwork of theological defense and construction, written over thirteen years in response to accusations that Christianity brought ruin upon Rome. This first volume contains the first ten books of sustained refutation—demolishing pagan claims that traditional worship secured either temporal prosperity or eternal happiness—followed by the beginning of his positive vision in Books Eleven through Thirteen, where he traces the origin of two societal orders to the primordial division among the angels. What emerges is not merely an apology for Christianity but a philosophy of history that subordinate the fate of empires to the hidden providence of the one true God, whose sovereignty extends from creation through the fall to the final judgment.
The phenomenon of twins provides Augustine with his most powerful argument against astrological determinism. Twins are conceived in the same act of copulation and born within moments of each other, yet their professions, honors, circumstances, and even their deaths frequently diverge dramatically. The famous physician Hippocrates once observed two brothers who fell ill simultaneously and recovered at the same time, leading him to suspect they were twins. Posidonius, a Stoic philosopher devoted to astrology, explained this coincidence by appealing to their shared constellation. But Augustine finds the physician’s explanation far more credible: similarities in health arise from shared bodily constitution, common nourishment, identical environment, and similar habits of life. The differences in their fortunes, however, cannot be attributed to the stars, for the stars were nearly identical for both.
The astrologers attempt to rescue their system by appealing to the small interval of time between twin births. Nigidius Figulus, a Roman scholar, devised an analogy using a potter’s wheel. Spinning the wheel rapidly, he marked it twice with ink in what appeared to be a single motion; when the wheel stopped, the marks were found far apart. Similarly, he argued, even a brief interval between births corresponds to a significant distance in the heavens, accounting for the differences in twins’ lives. Augustine finds this argument utterly unconvincing. If such minute, unobservable moments of time produce such vast celestial differences, then astrologers cannot claim to predict anything from the observable positions of stars. But if they rely on observable positions for their predictions, then the tiny differences between twins should correspond to trivial variations, not the profound divergences actually found. Moreover, if twins are born so close together that no change occurs in the horoscope, astrologers must predict identical lives—which never happens. If enough time elapses to change the horoscope, they must predict different parents—which is impossible.
The biblical story of Esau and Jacob furnishes Augustine with a compelling illustration. These twins emerged from the womb in such quick succession that the first grasped the heel of the second. Yet their lives unfolded in utterly different directions. One became a servant; the other never served. One was beloved by his mother; the other was not. One lost the honored birthright; the other gained it. Their wives, children, and possessions were entirely different. If such profound differences can arise from virtually identical stellar positions, then the whole edifice of astrological prediction collapses.
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