Many cultures have attached importance to astronomical events, and the Indians, Chinese, and Maya developed elaborate systems for predicting terrestrial events from celestial observations. In the West, astrology most often consists of a system of horoscopes purporting to explain aspects of a person’s personality and predict future events in their life based on the positions of the sun, moon, and other celestial objects at the time of their birth. The majority of professional astrologers rely on such systems
Astrology has been dated to at least the 2nd millennium BCE, with roots in calendrical systems used to predict seasonal shifts and to interpret celestial cycles as signs of divine communications. A form of astrology was practised in the first dynasty of Mesopotamia (1950–1651 BCE). Chinese astrology was elaborated in the Zhou dynasty (1046–256 BCE). Hellenistic astrology after 332 BCE mixed Babylonian astrology with Egyptian Decanic astrology in Alexandria, creating horoscopic astrology. Alexander the Great’sconquest of Asia allowed astrology to spread to Ancient Greece and Rome. In Rome, astrology was associated with ‘Chaldean wisdom’. After the conquest of Alexandria in the 7th century, astrology was taken up by Islamic scholars, and Hellenistic texts were translated into Arabic and Persian. In the 12th century, Arabic texts were imported to Europe and translated into Latin. Major astronomers including Tycho Brahe, Johannes Kepler and Galileo practised as court astrologers. Astrological references appear in literature in the works of poets such as Dante Alighieri and Geoffrey Chaucer, and of playwrights such as Christopher Marlowe and William Shakespeare.
Throughout most of its history, astrology was considered a scholarly tradition. It was accepted in political and academic contexts, and was connected with other studies, such as astronomy, alchemy, meteorology, and medicine. At the end of the 17th century, new scientific concepts in astronomy and physics (such as heliocentrism and Newtonian mechanics) called astrology into question. Astrology thus lost its academic and theoretical standing, and common belief in astrology has largely declined.
Astrology, in its broadest sense, is the search for meaning in the sky. Early evidence for humans making conscious attempts to measure, record, and predict seasonal changes by reference to astronomical cycles, appears as markings on bones and cave walls, which show that lunar cycles were being noted as early as 25,000 years ago. This was a first step towards recording the Moon’s influence upon tides and rivers, and towards organising a communal calendar. Farmers addressed agricultural needs with increasing knowledge of the constellations that appear in the different seasons—and used the rising of particular star-groups to herald annual floods or seasonal activities. By the 3rd millennium BCE, civilisations had sophisticated awareness of celestial cycles, and may have oriented temples in alignment with heliacal risings of the stars.
Scattered evidence suggests that the oldest known astrological references are copies of texts made in the ancient world. The Venus tablet of Ammisaduqa thought to be compiled in Babylon around 1700 BCE. A scroll documenting an early use of electional astrology is doubtfully ascribed to the reign of the Sumerian ruler Gudea of Lagash (c. 2144 – 2124 BCE). This describes how the gods revealed to him in a dream the constellations that would be most favourable for the planned construction of a temple. However, there is controversy about whether these were genuinely recorded at the time or merely ascribed to ancient rulers by posterity. The oldest undisputed evidence of the use of astrology as an integrated system of knowledge is therefore attributed to the records of the first dynasty of Mesopotamia (1950–1651 BCE). This astrology had some parallels with Hellenistic Greek (western) astrology, including the zodiac, a norming point near 9 degrees in Aries, the trine aspect, planetary exaltations, and the dodekatemoria (the twelve divisions of 30 degrees each). The Babylonians viewed celestial events as possible signs rather than as causes of physical events.
The system of Chinese astrology was elaborated during the Zhou dynasty (1046–256 BCE) and flourished during the Han Dynasty (2nd century BCE to 2nd century CE), during which all the familiar elements of traditional Chinese culture – the Yin-Yang philosophy, theory of the five elements, Heaven and Earth, Confucian morality – were brought together to formalise the philosophical principles of Chinese medicine and divination, astrology and alchemy.
Cicero stated the twins objection (that with close birth times, personal outcomes can be very different), later developed by Saint Augustine. He argued that since the other planets are much more distant from the earth than the moon, they could have only very tiny influence compared to the moon’s. He also argued that if astrology explains everything about a person’s fate, then it wrongly ignores the visible effect of inherited ability and parenting, changes in health worked by medicine, or the effects of the weather on people.
Plotinus argued that since the fixed stars are much more distant than the planets, it is laughable to imagine the planets’ effect on humankind should depend on their position with respect to the zodiac. He also argues that the interpretation of the moon’s conjunction with a planet as good when the moon is full, but bad when the moon is waning, is clearly wrong, as from the moon’s point of view, half of her surface is always in sunlight; and from the planet’s point of view, waning should be better, as then the planet sees some light from the moon, but when the moon is full to us, it is dark, and therefore bad, on the side facing the planet.
Favorinus argued that it was absurd to imagine that stars and planets would affect human bodies in the same way as they affect the tides, and equally absurd that small motions in the heavens cause large changes in people’s fates. Sextus Empiricus argued that it was absurd to link human attributes with myths about the signs of the zodiac. Carneades argued that belief in fate denies free will and morality; that people born at different times can all die in the same accident or battle; and that contrary to uniform influences from the stars, tribes and cultures are all different.