Augustine was born in what is now Tunisia, at that time part of the Roman Empire. He taught in Rome, studied Neoplatonic philosophy, was converted to Christianity in 386, and returned to Africa, where he became a bishop. His immense literary output molded the thinking of the Church ever afterwards. Best known of his works are the Confessions, an autobiographical account of his life and thought, and The City of God, a vast survey of history, the role of Christian revelation, and its teachings about the destiny of humanity.
In The City of God, like other fathers of the Church, Augustine maintains that the Old Testament foreshadows the New and only makes complete sense when read retrospectively from a Christian standpoint. In particular, many of the Old Testament prophecies were really about Christianity, even though they could not have been understood in that sense when they were written. They were divinely inspired, and their meaning has been decipherable since the coming of Christ; Augustine claims that they have been instrumental in making
many converts. Other prophecies, likewise inspired, are in the New Testament itself, notably in its last book, the Revelation or Apocalypse attributed to Saint John.
But what about prophecies unrelated to Christianity, by astrologers, for instance? If they are not inspired by God, does their fulfillment, when it happens, put a query over the Christian monopoly? Augustine regards them as illusory and worse than illusory even when they are right—especially when they are right. He attacks astrology as a technique, stressing such rational objections as the difficulty raised by twins, who have the same horoscope at birth but may go on to have very different lives. However, he looks deeper than that. He acknowledges that astrologers sometimes score, but he has a reason for rejecting their claims and advising Christians to mistrust them. This reason has wider applications.
According to Augustine, successful prophecy that is not of divine origin is diabolic, the work of “demons” or evil spirits. These beings can look ahead, if in a rather hit-or-miss way: “The demons… have much more knowledge of the future than men can have, by their greater acquaintance with certain signs which are hidden from us; sometimes they also foretell their own intentions. It is true that they are often deceived, while the angels are never deceived.” Human foreknowledge may be simply intelligent anticipation, but when it is more than that, it may be coming from “unclean demons” who are making use of their own foreknowledge to lead others astray. In the case of astrology, they mislead mortals by creating a bogus impression of validity. “When astrologers give replies that are often surprisingly true, they are inspired, in some mysterious way, by spirits, but spirits of evil, whose concern is to instil and confirm in men’s minds those false and baneful notions about ‘astral destiny.’ These true predictions do not come from any skill in the notation and inspection of horoscopes; that is a spurious art.”
Unhallowed prophecy, which may be plausible and even correct, but is communicated by evil beings for evil ends, reappears as a theme in the witch mania of the sixteenth and seventeenth centuries. It is a prominent motif in Shakespeare’s Macbeth.