Astrology, the effort to relate earthly occurrences to the stars and planets, is one of the oldest known intellectual endeavors. The oldest evidence for the Western tradition of astrology comes from Mesopotamia in the late third millennium b.c.e. Mesopotamian astronomical documents correlated celestial phenomena like eclipses with public events, including political changes and natural catastrophes. The first surviving "natal" horoscope, recounting the position of the planets at an individual's birth, is also Mesopotamian and dates from the late fifth century b.c.e. One Mesopotamian people, the Babylonians or Chaldeans, long remained famed for their astrological ability. Astrologers generally were called Chaldeans as early as the first century b.c.e. in Rome.
Greek interest in astrology began in the Hellenistic period, as Alexander the Great's (r. 336–323) conquests exposed Greek thinkers to Mesopotamian culture. The Greeks put astronomy in a cosmological framework, emphasizing the motions of the planets rather than static correlations. Hellenistic Alexandria was a center of astrology, and the Hermetic texts that originated there incorporated astrology into their magical and religious system. The Hellenistic period also saw the first evidence of Jews embracing astrology, a practice traditional Judaism condemned.
The Roman upper classes also initially condemned astrology, which they associated with popular divination and superstition. This position is reflected in Marcus Tullius Cicero's (106–43 b.c.e.) On Divination. Following the Roman conquest of the Hellenistic east in the first century b.c.e., Roman interest in astrology increased. The earliest evidence for Roman astrologers dates from this period. The Stoic school of philosophy, popular among the Roman elite, endorsed astrology along with other forms of divination. (The Epicureans, great rivals of the Stoics, condemned it.) Astrology became particularly prominent in the Roman Empire, as Augustus Caesar (63 b.c.e.–14 c.e.) employed it in his propaganda, subsequent emperors employed court astrologers, and rebels and aspirants to the imperial throne consulted astrologers to estimate their chances for success.
The imperial period saw the first surviving Latin astrological work, the Roman poet Manlius's Stoic-influenced Astronomica. Manlius had little astronomical or mathematical skill, however, and the most important astrological writer in the Roman Empire was the Greek astronomer Claudius Ptolemy (2nd century c.e.), author of the most influential ancient astrological book, Tetrabiblios. Ptolemy, more a codifier than an innovator in astrology, defended it as a science of the influence of the stars on the terrestial world based on conjecture rather than certainty. The early Christians attacked astrology, associating it with determinism and Gnosticism. St. Augustine of Hippo's (354–430) denunciation of astrology in The City of God was particularly influential in the Latin West. The Christian Roman Empire included astrology in its strong antidivination laws, which were however only sporadically enforced.
During the early Middle Ages, astrology, like many ancient disciplines, languished in the Latin West less because of the church's condemnation than because few Westerners were able to draw an astrological chart or read Greek astrological works. The most important theoreticians and practitioners in the early Middle Ages were Arabic speakers in the Islamic world. Arabs developed several astrological ideas later accepted in the West, such as the correlation of patterns in human history with the conjunctions of Jupiter and Saturn, the so-called great conjunctions. Greek and Arabic works of astrological theory were translated into Latin only in the twelfth and thirteenth centuries. Medieval intellectuals like Albertus Magnus (c. 1200–1280) and Roger Bacon (c. 1220–1292) endorsed astrology but faced the problem of reconciling astrological determinism with the Christian doctrine of free will. They claimed that the stars influenced only the body, and not the soul. St. Thomas Aquinas (c. 1224–1274) conceded that the stars influenced human passions, and that many astrological predictions were correct because most people were ruled by their passions. He claimed, however, that the wise man could resist his passions, and thus the stars could not determine his actions. The medieval emphasis on the power of the stars over the body helped astrology become closely allied with medicine. Charles V of France (r. 1364–1380), whose library contained many books on astrology, contributed to the foundation of a college of astrological medicine in the 1360s.
Not all late medieval intellectuals accepted the new astrology. Six propositions of Bishop Étienne Tempier's famous prohibition of 1277 condemned astrology, mostly on the grounds of its determinism. The Scholastic philosopher Nicole d'Oresme (c. 1325–1382) vigorously opposed astrology. He reiterated the Christian attack on astrological determinism and added a new argument, that the velocities of the heavenly bodies were mathematically irrational and incommeasurable, and thus it was impossible to know them exactly enough for astrology to work.
Astrology in the Renaissance and Reformation
As in other ancient sciences, Renaissance humanists claimed to be recovering the true, ancient astronomy from corruption by Arab and medieval Latin writers (although Arab-derived great conjunction theory remained very popular.) Renaissance philosophers, particularly those influenced by Neoplatonism, also extended the discipline's scope. The third book of Marsilio Ficino's (1433–1499) Three Books on Life (1489) treated the planets as a guide to all aspects of human life. Girolamo Cardano (1501–1576), who wrote a commentary on the Tetrabiblios, scandalized many by drawing a natal horoscope of Jesus Christ. While Martin Luther (1483–1546) and John Calvin (1509–1564) both condemned astrology, many of their Protestant followers (including Philipp Melanchthon; 1497–1560) practiced it. Protestant astrologers were particularly interested in reconciling astrology with the apocalyptic interpretation of the Bible, using the stars and great conjunctions to help predict the date of the end of the world.
Astrology was an important support for professional astronomers in the late Middle Ages and Renaissance, as many patrons were interested in astronomical data principally for its astrological uses. The leaders of the scientific revolution differed in their opinions of astrology. The last major Western astronomers to seriously practice astrology were Tycho Brahe (1546–1601) and Johannes Kepler (1571–1630), both of whom drew horoscopes for the monarchs they served. Mechanical philosophers like Marin Mersenne (1588–1648) and the "Christian Epicurean" Pierre Gassendi (1592–1655) denied the doctrine of the influence of the stars on the Earth that astrology was based on, as it had no mechanical explanation. Although several of the founding members of the Royal Society practiced astrology, it lost its central intellectual role in the late seventeenth century. Astronomers increasingly justified their science as useful in navigation and cartography rather than astrology. Copernican astronomy did not "dis-prove" astrology, but the shift from an earth-centered to a sun-centered cosmos did call into question traditional geocentric astrological interpretation. Astrology also suffered from the general decline of magical thinking as Europe entered the eighteenth century. Although many ordinary people continued to believe in astrology, it was not taken seriously by most scientists and intellectuals.
See also Magic ; Pseudoscience ; Science .
Barton, Tamsyn. Ancient Astrology. New York: Routledge, 1994.
Grafton, Anthony. Cardano's Cosmos: The Worlds and Works of a Renaissance Astrologer. Cambridge, Mass.: Harvard University Press, 1999.
Tester, S. Jim. A History of Western Astrology. Woodbridge, Suffolk, U.K.: Boydell, 1987.
Zambelli, Paola, ed. "Astrologi Hallucinati": Stars and the End of the World in Luther's Time. New York: de Gruyter, 1986.
William E. Burns