In the Footsteps of Angels: Medieval Arabic Astrology

As the newly formed Muslim caliphate extended beyond the Arabian Peninsula, it encountered Persian, Hellenistic, and Indian forms of astrology, integrating them into a refined science that would reach its medieval peak in Baghdad, a city whose fortune and fate would be foretold by the stars.

Published Categorized as History
Illustrations show the path of the moon around earth and the earth around the Sun leading to different phases of the moon and the solar and lunar eclipses. Text is in Arabic.
Illustration of different phases of the moon, from manuscript of the Kitab al-Tafhim by Al-Biruni (973-1048).

It is He who made the stars, so that they can guide you when land and sea are dark: We have made the signs clear for those who have knowledge.

The Holy Qu’ran. 6:97

Unifying the diverse fields of mathematics, philosophy, optics, and astronomy, Hellenistic astrology needed an environment conducive to higher learning to survive through the trappings of state-funded libraries, observatories, and schools. Once Rome fell, so too fell the instruments supporting the sciences in Western Europe. The region would remain too embroiled in territorial squabbles—and too suspicious of pagan sources of knowledge—to preserve the sciences of antiquity. The wealth and infrastructure of the empire would persist in the east within the territory of the Byzantine empire for another millennium but it would be a new power outside of Christendom that would take up—and ultimately improve upon—the “wisdom of the ancients”.

In the century following the flight of Muhammad and his followers from Mecca, Islam would go from local sect to world religion. Arab tribal rulers came to govern a territory surpassing in size that of Rome with a distinctly multicultural population, each community boasting histories stretching back thousands of years. Though the invading Arabs would be initially hostile to indigenous scholarship, destroying Persian astrological texts they considered incompatible with Islam, the Arab elite would eventually come to embrace the intellectual and cultural heritage of the lands and people they now ruled. 

Zodiac imagery and lunar mansions wheel, rich imagery.
Celestial map, signs of the Zodiac and lunar mansions in the Zubdat-al Tawarikh, dedicated to the Ottoman Sultan Murad III in 1583.

The Islamic Golden Age, a period of stability and prosperity stretching from the 8th to the 12th century, saw Jewish, Christian, Hindu, Persian, Syrian, and pagan intellectuals working alongside Arab thinkers in the prosperous Abbasid capital of Baghdad, translating, preserving, and improving upon an immense variety of fields, all in the scientific lingua franca of Arabic. By allowing initiates to read the will of Allah from the composition of the heavens, astrology was second only to the reading of the Quran in the sciences of this golden era.

The work of prominent Arabic thinkers shaped astrology as wealth, cultural exchange, and innovation would allow for technical, mathematical, and philosophical advances surpassing those achieved in the Greco-Roman world. It was to be this flowering of knowledge that would then pass astrology—and many other founts of ancient learning—on to the West, sparking the Renaissance and the beginnings of modernity.

Astrology within Islam

The tribespeople of the Arabian Peninsula, as nomadic traders, were familiar with astrology, and they both used a lunar calendar and navigated through the desert by the stars. Islam ostensibly forbade the worship of the sun and moon but one Quranic doctrine would allow philosophers to draw upon and adapt pre-Islamic sciences to fit into a distinctly Islamic worldview. This doctrine, known as tawhid, took the oneness of God to imply the oneness of wisdom, with all knowledge deriving from an original, uncorrupted source despite its seemingly fragmented nature. Tawhid allowed scholars writing in Arabic to draw upon the work of their Greek, Syrian, Persian, and Hindu predecessors, regardless of the religious content of those sources.

Abu Ma’shar was particularly instrumental to the integration of astrology into the Islamic worldview by attributing the field to the antediluvian prophet Idris/Enoch, fused with the neo-Platonic figure of Hermes Trismegistus. The prophet was said to have ascended to the seventh heaven, the Saturnian sphere of the cosmos, where he learned the art of reading the stars and the planets. Then, instead of ascending to paradise, he descended to Earth to share his newfound knowledge with humanity—although popular Islamic folklore has it that he left his sandals in heaven to allow himself to return.

Main image shows Sun with a man seated beside a beast. Beneath that there are 5 images showing man involved in 5 different occupations as per the 5 traditional planets.
Page of a 15th-century manuscript of the “Book of nativities” by Abu Ma’shar

Both India and Sassanian Persia would absorb Hellenistic astrology in the first few centuries A.D. and both cultures would play a role in shaping Arabic astrology. The first astrology text to be translated into Arabic was “Siddhanda”, a Sanskrit text, in 770 A.D., and many prominent astrologers writing in Arabic, most notably Abu Ma’shar, Omar of Tiberias, and al Biruni, drew heavily from their Persian roots. There were also Hindu astrologers working in Baghdad alongside Christians, Zoroastrians, Jews, and pagans but the primary source for Arab astrology remained Greek. The Arabs partly encountered it after conquering Alexandria and its eponymous library in 647, and their dealings with the Mandaeans in the city of Harran. 

Located in what is now southeastern Turkey, Harran was a prominent center of pagan learning that survived well past the rise of monotheism in the region. Its inhabitants practiced a form of astral magic and held a distinctly neo-Platonic view of the universe. Respected as practitioners of what many Islamic thinkers considered an original belief handed down by God before the Flood, the Mandaeans would resist conversion until the 11th century. With the influence of Abu Ma’shar and other astrologers, their neo-Platonic worldview would come to underpin Arab astrology, with the planets treated as angels or otherwise signifiers of the one God that could be addressed or observed in His stead. Al Kindi, known as the “Father of Arabic Astrology”, would introduce the work of Aristotle, the second Hellenistic pillar supporting the Islamic sciences, and establish a vocabulary for philosophy in Arabic.

Arabic Innovations

While the philosophical basis for Arabic astrology relied on the works of Aristotle and a neo-Platonic worldview, its practice in the Islamic world depended on several innovations, both technological and theoretical. The astrolabe provided astronomers and navigators alike with an analog map of the heavens. For astrologers, it provided a quick way to calculate the ascendant, the first step in casting a horoscope.

The zij, meanwhile, were Arabic ephemerides, tables containing astronomical data and formulas for calculating the rising times of various celestial bodies. Initially inspired by Ptolemy’s tables, Arabic astronomers and astrologers improved upon the model, often providing information related to trigonometry, chronology, and geography alongside strictly astrological data. The wealth of the Islamic world also supported both astrological schools and observatories, the former providing training for the best and brightest and the latter allowing Arabic astrologers to predict celestial movement with unprecedented accuracy.

Jupiter rising with Mars turning cadent in the 7th house. Ruler of 7th is debilitated by being retrograde, in the 8th house and conjunct the South Node. Sun is in rulership in Leo in the house of its Joy in the 9th house.
Foundation of Baghdad – a classic astrology election, 31 Jul 762 2:40 PM

The city of Baghdad, the newly constructed Abbasid capital on the Tigris, would prove to be a particularly essential center of learning and was even founded according to a chart cast by Jewish Arab astrologer Mash’allah, among others. The placement of Jupiter rising in its domicile of Sagittarius ensured over four centuries of prosperity—although a malignant Mars in the 7th house of open enemies (in line with the Arabic tradition) would have other plans. But in its prime, the city was a beacon of learning, drawing intellectuals from across the Islamic world.

The first Arabic astrology school was founded there in 777 A.D. by Jewish astrologer Jacob ben Tarik, and the Caliph Al-Mamun would construct the first observatory there in 829 A.D. Al-Mamun would also be responsible for founding the House of Wisdom, either a library or group of intellectuals that supported the translation of ancient texts from Persian, Sanskrit, Syriac, and Greek into Arabic that fostered the careers of both al Kindi and Abu Ma’shar. Contact with Greek sources would give Arabs access to the natural philosophy of Aristotle and Ptolemy, plus the mathematics of trigonometry, while connections to the Hindu east would give them the concept of zero, a decimal system, numerals, and algebra.

By the early 9th century, when Omar of Tiberias wrote the texts that would eventually influence Latin astrologers, the astrology that he was using was by and large Hellenistic in content. The alterations from Hellenistic practice may have been due to the influence of Persian astrology, but many features would become fundamental for the development of horary and mundane astrology.

The concept of orbs of light to measure aspects between two planets, rather than measuring aspects from sign, degree, or even bound, first appeared in Arabic astrology and would be carried into the medieval European tradition. Similarly, the first departure from the whole sign house system to quadrant houses is visible in Arabic language texts. Arabic astrologers also used a complex system of interferences with aspects, known as Alitifel, that few modern astrologers employ.

Astrologer holding the celestial sphere and probing it.
Title page for a 1504 German edition of De scientia motvs orbis, originally by Māshāʼallāh (740–815)

Additionally, the work of Mash’allah and Abu Ma’shar would introduce a historical view of astrology based on conjunctions of Jupiter and Saturn, the slowest-moving visible planets. A prominent feature of Persian astrology, these conjunctions occur in some form every 20, 260, and 960 years and were seen as signifying momentous events in world history. Indeed, Abu Ma’shar would use these so-called “Great Conjunctions” to analyze the astrological conditions around both Jesus’ and Muhammad’s births and foretell the downfall of his own patron, the Abbasid Caliphate. Aries Ingress charts would become another important technique for mundane astrology, with Solar Return charts serving as their counterpart in natal astrology. 

The system of lots, or parts, mathematically defined locations in a chart, would also become more prominent in Arabic astrology, especially in horary practices. While Ptolemy defined only the lot of Fortune, Arabic astrologers would use dozen of lots to predict everything from the debt of the native to the prospects of that year’s lentil harvest. Al Biruni, a philosopher and astrologer working in 11th century Afghanistan would provide a comprehensive list in his Elements of the Art of Astrology, complaining that “they increase in number every day”.

The End of an Era

The unified Arabic worldview—a fusion of neo-Platonic thought and Islamic doctrine—would intrigue the European Crusaders when they arrived in the Holy Land. However, the most important transit point of Islamic sciences, astrology included, would become the Jewish communities of Western Europe. From Moorish Spain to Renaissance Italy, most cities boasted a sizable Jewish community, some with considerably higher status than is typically assumed. 

A scene of Ibn Ezra practicing Astrology with an Arabic manuscripts being held by the men that flank him to either side.
An illustration of Ibn Ezra (center) making use of an astrolabe, ca 1235

Perhaps the most famous Jewish astrologer, also a philosopher and poet, Ibn Ezra began the life of a roving scholar after increasing persecution pushed him out of his native Navarre. He wrote a dozen books on astrology, from mundane to medicinal, in Hebrew that contained techniques and philosophies prominent in Arabic sources.

These works would see a Latin translation thanks to Pietro d’Abana, while other European Jewish intellectuals collaborated with priests to translate important Arabic works into Latin. This new flood of scientific knowledge from the East, some direct from Hellenistic sources and some from their improved Arabic equivalents, would ignite the intellectual fervor of the European Renaissance and bring about the birth of modernity.

The works of Ptolemy, Omar of Tiberias, and Abu Ma’shar would inspire a whole new generation of astrologers and see the ancient science integrated into a distinctly Christian worldview. While some Latin astrologers would dismiss astrological techniques attributed to Arabic sources, William Lilly himself would cite the sayings of Abu Ma’shar, al Farghani, and al Kindi in Christian Astrology centuries later. Meanwhile, in the east, the Golden Era of Islam was drawing to a close and Mars was to have its revenge on the glimmering city of Baghdad. In 1248, Hulagu Khan, the grandson of Genghis Khan, sacked the city, burning its libraries and making a pyramid from the skulls of its literati. The city would experience a similarly disastrous conquest by Timurlane in 1401 and never reclaim its former level of glory. The city that once preserved the “wisdom of the ancients” had seen its downfall foretold by the very art it helped survive the passage of the centuries.


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