The history of astrology

The History of Astrology

Astrological beliefs in correspondences between celestial observations and terrestrial events have influenced various aspects of human history, including world-views, language and many elements of social culture.

Among Indo-European peoples, astrology has been dated to the 3rd millennium BC, with roots in calendrical systems used to predict seasonal shifts and to interpret celestial cycles as signs of divine communications. Until the 17th century, astrology was considered a scholarly tradition, and it helped drive the development of astronomy. It was commonly accepted in political and cultural circles, and some of its concepts were used in other traditional studies, such as alchemy, meteorology and medicine. By the end of the 17th century, emerging scientific concepts in astronomy, such as heliocentrism, undermined the theoretical basis of astrology, which subsequently lost its academic standing and became regarded as a pseudoscience. Empirical scientific investigation has shown that predictions and recommendations based on these systems are not accurate.

In the 20th century, astrology gained broader consumer popularity through the influence of regular mass media products, such as newspaper horoscopes.

Astrology, in its broadest sense, is the search for human meaning in the sky; it seeks to understand general and specific human behaviour through the influence of planets and other celestial objects. It has been argued that astrology began as a study as soon as human beings made conscious attempts to measure, record, and predict seasonal changes by reference to astronomical cycles.

Early evidence of such practices appears as markings on bones and cave walls, which show that lunar cycles were being noted as early as 25,000 years ago; the first step towards recording the Moon’s influence upon tides and rivers, and towards organising a communal calendar. With the Neolithic agricultural revolution new needs were also met by increasing knowledge of constellations, whose appearances in the night-time sky change with the seasons, allowing the rising of particular star-groups to herald annual floods or seasonal activities. By the 3rd millennium BC, widespread civilisations had developed sophisticated awareness of celestial cycles, and are believed to have consciously oriented their temples to create alignment with the heliacal risings of the stars.

There is scattered evidence to suggest that the oldest known astrological references are copies of texts made during this period, particularly in Mesopotamia (Sumer, Akkad, Assyria and Babylonia). Two, from the Venus tablet of Ammisaduqa (compiled in Babylon around 1700 BC) are reported to have been made during the reign of king Sargon of Akkad (2334-2279 BC). Another, showing an early use of electional astrology, is ascribed to the reign of the Sumerian ruler Gudea of Lagash (c. 2144 – 2124 BC). 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, controversy attends the question of whether they 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 that emerge from the first dynasty of Mesopotamia (1950-1651 BC).

Hellenistic Egypt

In 525 BC Egypt was conquered by the Persians so there is likely to have been some Mesopotamian influence on Egyptian astrology. Arguing in favour of this, historian Tamsyn Barton gives an example of what appears to be Mesopotamian influence on the Egyptian zodiac, which shared two signs – the Balance and the Scorpion, as evidenced in the Dendera Zodiac (in the Greek version the Balance was known as the Scorpion’s Claws).

After the occupation by Alexander the Great in 332 BC, Egypt came under Hellenistic rule and influence. The city of Alexandria was founded by Alexander after the conquest and during the 3rd and 2nd centuries BC, the scholars of Alexandria were prolific writers. It was in Ptolemaic Alexandria that Babylonian astrology was mixed with the Egyptian tradition of Decanic astrology to create Horoscopic astrology. This contained the Babylonian zodiac with its system of planetary exaltations, the triplicities of the signs and the importance of eclipses. Along with this it incorporated the Egyptian concept of dividing the zodiac into thirty-six decans of ten degrees each, with an emphasis on the rising decan, the Greek system of planetary Gods, sign rulership and four elements.

The decans were a system of time measurement according to the constellations. They were led by the constellation Sothis or Sirius. The risings of the decans in the night were used to divide the night into ‘hours’. The rising of a constellation just before sunrise (its heliacal rising) was considered the last hour of the night. Over the course of the year, each constellation rose just before sunrise for ten days. When they became part of the astrology of the Hellenistic Age, each decan was associated with ten degrees of the zodiac. Texts from the 2nd century BC list predictions relating to the positions of planets in zodiac signs at the time of the rising of certain decans, particularly Sothis. The earliest Zodiac found in Egypt dates to the 1st century BC, the Dendera Zodiac.

Particularly important in the development of horoscopic astrology was the astrologer and astronomer Ptolemy, who lived in Alexandria in Egypt. Ptolemy’s work the Tetrabiblos laid the basis of the Western astrological tradition, and as a source of later reference is said to have “enjoyed almost the authority of a Bible among the astrological writers of a thousand years or more”.It was one of the first astrological texts to be circulated in Medieval Europe after being translated from Arabic into Latin by Plato of Tivoli (Tiburtinus) in Spain, 1138. 

According to Firmicus Maternus (4th century), the system of horoscopic astrology was given early on to an Egyptian pharaoh named Nechepso and his priest Petosiris. The Hermetic texts were also put together during this period and Clement of Alexandria, writing in the Roman era, demonstrates the degree to which astrologers were expected to have knowledge of the texts in his description of Egyptian sacred rites:

“This is principally shown by their sacred ceremonial. For first advances the Singer, bearing some one of the symbols of music. For they say that he must learn two of the books of Hermes, the one of which contains the hymns of the gods, the second the regulations for the king’s life. And after the Singer advances the Astrologer, with a horologe in his hand, and a palm, the symbols of astrology. He must have the astrological books of Hermes, which are four in number, always in his mouth.”

Medieval and Renaissance Europe

©Photo. R.M.N. / R.-G. OjŽda
An image related to astrology from the Très Riches Heures du Duc de Berry. It shows the purported relation between body parts and the signs of the zodiac.

Whilst astrology in the East flourished following the break up of the Roman world, with Indian, Persian and Islamic influences coming together and undergoing intellectual review through an active investment in translation projects, Western astrology in the same period had become “fragmented and unsophisticated … partly due to the loss of Greek scientific astronomy and partly due to condemnations by the Church.”

Translations of Arabic works into Latin started to make their way to Spain by the late 10th century, and in the 12th century the transmission of astrological works from Arabia to Europe “acquired great impetus”.

By the 13th century astrology had become a part of everyday medical practice in Europe. Doctors combined Galenic medicine (inherited from the Greek physiologist Galen – AD 129-216) with studies of the stars. By the end of the 1500s, physicians across Europe were required by law to calculate the position of the Moon before carrying out complicated medical procedures, such as surgery or bleeding.

Influential works of the 13th century include those of the British monk Johannes de Sacrobosco (1195–1256) and the Italian astrologer Guido Bonatti from Forlì (Italy). Bonatti served the communal governments of Florence, Siena and Forlì and acted as advisor to Frederick II, Holy Roman Emperor. His astrological text-book Liber Astronomiae (‘Book of Astronomy’), written around 1277, was reputed to be “the most important astrological work produced in Latin in the 13th century”. Dante Alighieri immortalised Bonatti in his Divine Comedy (early 14th century) by placing him in the eighth Circle of Hell, a place where those who would divine the future are forced to have their heads turned around (to look backwards instead of forwards).

In medieval Europe, a university education was divided into seven distinct areas, each represented by a particular planet and known as the seven liberal arts. Dante attributed these arts to the planets. As the arts were seen as operating in ascending order, so were the planets in decreasing order of planetary speed: grammar was assigned to the Moon, the quickest moving celestial body, dialectic was assigned to Mercury, rhetoric to Venus, music to the Sun, arithmetic to Mars, geometry to Jupiter and astrology/astronomy to the slowest moving body, Saturn.

Medieval writers used astrological symbolism in their literary themes. For example, Dante’s  Divine Comedy builds varied references to planetary associations within his described architecture of Hell, Purgatory and Paradise, (such as the seven layers of Purgatory’s mountain purging the seven cardinal sins that correspond to astrology’s seven classical planets).Similar astrological allegories and planetary themes are pursued through the works of Geoffrey Chaucer. 

Chaucer’s astrological passages are particularly frequent and knowledge of astrological basics is often assumed through his work. He knew enough of his period’s astrology and astronomy to write a Treatise on the Astrolabe for his son. He pinpoints the early spring season of the Canterbury Tales in the opening verses of the prologue by noting that the Sun “hath in the Ram his halfe cours yronne”. He makes the Wife of Bath refer to “sturdy hardiness” as an attribute of Mars, and associates Mercury with “clerkes”. In the early modern period, astrological references are also to be found in the works of William Shakespeare and John Milton.

One of the earliest English astrologers to leave details of his practice was Richard Trewythian (b. 1393). His notebook demonstrates that he had a wide range of clients, from all walks of life, and indicates that engagement with astrology in 15th-century England was not confined to those within learned, theological or political circles.

During the Renaissance, court astrologers would complement their use of horoscopes with astronomical observations and discoveries. Many individuals now credited with having overturned the old astrological order, such as Tycho Brahe, Galileo Galilei and Johannes Kepler, were themselves practicing astrologers.

At the end of the Renaissance the confidence placed in astrology diminished, with the breakdown of Aristotelian Physics and rejection of the distinction between the celestial and sublunar realms, which had historically acted as the foundation of astrological theory. Keith Thomas writes that although heliocentrism is consistent with astrology theory, 16th and 17th century astronomical advances meant that “the world could no longer be envisaged as a compact inter-locking organism; it was now a mechanism of infinite dimensions, from which the hierarchical subordination of earth to heaven had irrefutably disappeared”. Initially, amongst the astronomers of the time, “scarcely anyone attempted a serious refutation in the light of the new principles” and in fact astronomers “were reluctant to give up the emotional satisfaction provided by a coherent and interrelated universe”. By the 18th century the intellectual investment which had previously maintained astrology’s standing was largely abandoned. Historian of science Ann Geneva writes:

“Astrology in seventeenth century England was not a science. It was not a Religion. It was not magic. Nor was it astronomy, mathematics, puritanism, neo Platism, psychology, meteorology, alchemy or witchcraft. It used some of these as tools; it held tenets in common with others; and some people were adept at several of these skills. But in the final analysis it was only itself: a unique divinatory and prognostic art embodying centuries of accreted methodology and tradition.”


The calendars of Pre-Columbian Mesoamerica are based upon a system which had been in common use throughout the region, dating back to at least the 6th century BC. The earliest calendars were employed by peoples such as the Zapotecs and Olmecs, and later by such peoples as the Maya, Mixtec and Aztecs. Although the Mesoamerican calendar did not originate with the Maya, their subsequent extensions and refinements to it were the most sophisticated. Along with those of the Aztecs, the Maya calendars are the best-documented and most completely understood.

The distinctive Mayan calendar used two main systems, one plotting the solar year of 360 days, which governed the planting of crops and other domestic matters; the other called the Tzolkin of 260 days, which governed ritual use. Each was linked to an elaborate astrological system to cover every facet of life. On the fifth day after the birth of a boy, the Mayan astrologer-priests would cast his horoscope to see what his profession was to be: soldier, priest, civil servant or sacrificial victim. A 584-day Venus cycle was also maintained, which tracked the appearance and conjunctions of Venus. Venus was seen as a generally inauspicious and baleful influence, and Mayan rulers often planned the beginning of warfare to coincide with when Venus rose. There is evidence that the Maya also tracked the movements of Mercury, Mars and Jupiter, and possessed a zodiac of some kind. The Mayan name for the constellation Scorpio was also ‘scorpion’, while the name of the constellation Gemini was ‘peccary’. There is some evidence for other constellations being named after various beasts. The most famous Mayan astrological observatory still intact is the Caracol observatory in the ancient Mayan city of Chichen Itza in modern-day Mexico.

The Aztec calendar shares the same basic structure as the Mayan calendar, with two main cycles of 360 days and 260 days. The 260-day calendar was called Tonalpohualli and was used primarily for divinatory purposes. Like the Mayan calendar, these two cycles formed a 52-year ‘century’, sometimes called the Calendar Round.


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