Book Review: Astronomy and Astrology in the Islamic World - Stephen P Blake

Stephen P. Blake, Astronomy and Astrology in the Islamic World. The New Edinburgh Islamic Surveys, Edinburgh; Edinburgh University Press. 2016. 163 pp. £24.99 (paperback).
ISBN: 978-0-7486-4909-9. https://edinburghuniversitypress.com/book-astronomy-and-astrology-in-the-islamic-world.html

Astronomy and Astrology in the Islamic World forms part of The New Edinburgh Islamic Surveys, a broad series of introductory texts covering specialist topics in the study of Islam including history, politics, religion and culture, initiated in 1987 by the Edinburgh University Press. This short introductory overview by Stephen P. Blake, follows his monographic works on the history of Islamic astronomy. It offers a non-technical overview of the Islamic advances in the development of astronomy and astrology, the “science of the stars” (p.25), in the Eurasian world. Acting as an accessible introduction to the history of this fascinating subject this book complements current scholarship on the history of astronomy and astrology in the early Islamicate era and its relationship and influence on early modern Europe.  Blake argues that it was the work of the astronomers/astrologers of the Islamic world building on theories and concepts from the Hellenistic era, such as the epicycles and geocentricity of Claudius Ptolemy, that influenced the breakthroughs of later European astronomers such as Nicolaus Copernicus, Tycho Brahe and Johannes Kepler. Blake’s approach forefronts the importance of the observatory as a cultural and academic institution that would play a pivotal role throughout the broad stretch of the Islamic Empire, from the Indian subcontinent to Spain. The observatories and madrasas were paramount for the advancements and inventions of new astronomical instruments and the mathematics required to achieve observations of increasing accuracy. Imperative to this was the reverence of knowledge and the appreciation of learning from other cultures, coupled with the periodic revision of key texts, such as Ptolemy’s Almagest, and Euclid’s Elements, that would lead to innovative solutions and shape the understanding of the cosmos. 

The accessibility and scope of this book is commendable. Blake masterfully traces the influences and continuation of important developments through the complex and diverse histories of the wide-reaching Islamic world, from the early medieval to early modern period. His focus on the observatories serves as a linchpin running through the chapters, allowing for detailed introduction to the different geographical regions and the dynasties, politics and their patronage of the study of astronomy and astrology. From the observatory in Isfahan in the Seljuk dynasty under the reign of Malik-Shah I (1072–92) to the five observatories of Jaipur, Ujjain, Varanasi, Mathura and Shahjanabad of Jai Singh in the Mughal Empire of the Indian subcontinent under the reign of Muhammad Shah (1719–1748). Coupled with Blake’s insightful scholarly elucidation on the history of the transmission of the Islamic astronomical treatise - the Zij – through each generation that would spur much of the work carried out at the observatories. 

While Blake’s work on the astronomical side of this history is praiseworthy, his treatment and exploration of the astrological side is, at times, less so. Demonstrated in his brief summary of the work and influence of Masha’allah as “his primary contribution, however, was in the field of astrology. Well-versed in the Sassanid pseudoscience” (p.28). Blake’s one paragraph summary of Masha’allah, lacks the depth and nuance such an influential figure in the history of astrology of the Islamic world deserves, as one of the astrologers responsible for electing the time and date for the foundation of the Abbasid capital in Baghdad. Blake does offer a better, and longer, examination in his summary of Abu Ma’shar. Outlining his “new rationale for the pseudoscience” and “far reaching theory of historical astrology” (p.29). His preference for astronomy over astrology throughout the book could inadvertently misguide those approaching this text as an introduction to the subject, obscuring the potential richness of astrology's historical role, which was the purview of the great historic thinkers, from Ptolemy to Kepler, who bookend Blake’s text.

Looking at the many strengths of this work, the introduction covers the Egyptian, Babylonian, Sassanian, India and Greek cultures’ influence on the astronomy and astrology of the early Islamic world. Blake introduces the significant role the Hellenistic Greeks played in the development of mathematics, astronomy and astrology prior to the Islamic age. Introducing the key Greek philosophers such as Plato, Eudoxus, Aristotle and Hipparchus, and outlining Ptolemy’s major work on astronomy the Almagest, along with the Tetrabiblos, Ptolemy’s treatise on astrology. Blake later demonstrates throughout the book how the Almagest was revised by the astronomers in the history of the Islamic world, each seeking to improve the accuracy and solve mathematical problems of the subsequent revisions and redactions.  This introductory chapter serves as a helpful foundation to the cultural contexts that would shape the developments of astronomy and astrology through the history of the Islamic world up to to the 18th century. Blake is commendable in his coverage of the importance of the early influences of Indic traditions both in terms of the developments in mathematics, astronomy and astrological practice. With a summary of the importance of Indic astronomy and mathematics via the astronomer Aryabhata’s (476–550CE) mathematical and astronomical treatises Aryabhatiya and Arya Siddhanta. Along with the innovations of Brahmagupta (598–665CE) such as the invention of the modern decimal positional numeral system. Whilst giving examples of important Indic astrological texts including the Greek influenced Yavanajataka and the Roman influenced Romakasiddhanta – again demonstrating the cross-cultural nature of this study.  Blake also covers the influence of the Zoroastrian’s theories of astrological history, such as the world year and the Jupiter/Saturn conjunctions that would play a prominent role in astrology throughout the Islamicate world. Along with the early translations by the Sassanids (224-651CE) of the earlier Greek works including texts by Dorotheus of Sidon, Vettius Valens, and Sanskrit works such as the Romakasiddhanta. 

In chapter two, From Muhammed to the Seljuqs Blake charts the rise of Islam from the early nomadic tribes of the Arabian Peninsula at the birth of the Prophet Muhammed (ca.570CE), and the expansion of the Islamic empire to the early 11th century. Blake points out how the Qur'an and the Five Pillars of Islam were important for the cultural adoption of astronomical practices, as they assisted with daily timekeeping, calendrics for the timing of the festival of Ramadan, and for orientation towards Mecca for daily prayer across a growing empire. Blake also emphasises the translation movement during the Abbasid Caliphate (750–1258) and the high point of the House of Wisdom in Baghdad under al Ma'mun (786–833). Where numerous texts on scientific knowledge from foreign cultures were translated into Arabic. The chapter also includes brief biographies of prominent and hugely influential astrologers including Masha’Allah, Abu Ma’Shar, al-Biruni and mathematicians such as al-Khwarizmi, Al-Farghani and Al-Battani. Along with summaries of the importance of several key works that are notable for their later influence such as Abu Ma’Shar’s Book of Religions and Dynasties which combined Zoroastrian and Indic chronological systems and Al-Khwarizimi’s version of the Zij al-Sindhind which demonstrated algebra and the ‘new’ Indic decimal numbering system, and astronomical tables derived from Indian values rather than Ptolemaic. 

Chapter three begins the main focus of the book, with a detailed look at the role of the observatory in Islam, their importance for the progression of mathematics, astronomy/astrology, and cultural and religious practices. Starting with the early observatory in Isfahan, Iran under the Seljuk ruler Malik Shah I, built by ‘Umar Ibn Ibrahim al-Nishapui al-Khayyam (ca.1048-1131). The Isfahan observatory became an institution, featuring securely funded staff, a headquarters and large astronomical instruments. Blake highlights the importance of the advances in the fabrication of the astronomical instruments for conducting observations for the creation of mathematical formulas and astronomical works. Building upon the earlier systematic observational programme developed during the time of the al-Ma’mum, and the House of Wisdom. Here, Blake also examines the reformation of the Seljuq chronological system and the reorganisation of the Islamic calendar by ‘Umar and the establishment of the Hijra Era.

The fourth chapter looks at al-Andalus and the Islamic kingdoms of Southern Spain, where the science of the stars developed tangentially from the eastern regions. Along with the emergence of independent Spanish-Muslim states. With the capital of the Umayyad Caliphate (756-1031) in Cordoba. The majority of the chapter focuses on Abu Ishaq Ibrahim al-Zarqali (ca.1029-1100) and his work in the city state of Toledo, Blake notes how al-Zaraqli’s fame was widespread both in Andalusia and the Latin West, through the Universal Astrolabe and the Toledan Tables (ca.1080). The Toledan Tables and al-Majriti’s Zij al-Sindhind became widely popular in medieval Europe, by the early 12th century notably in England, France and Italy, where they were adapted for different latitudes. A highlight of Blake’s overview of the period is the comparison of the developments in Islamic astronomy between the east and the west in the 11th century through a comparative study of Al-Zarqali in Toledo and ‘Umar Khayyam and al-Khazini in Isfahan. Blake maintains that in the history of astronomy and astrology, Andalusia was a conduit through which knowledge eventually transferred from the Islamic east to the Christian west. 

The focus of Chapter five shifts to the east and explores the history and influence of the Maragha Observatory, which Blakes argues to be the most advanced scientific institution in the Eurasian world. Founded in north-western Iranian (modern day Azerbaijan) in the 13th century and centred around the influential work of astrologer/astronomer, Nasir al-Din Tusi (1201–74), under the generous patronage of the Mongol conqueror Hulagu. The chapter covers the foundation of the new observatory at Maragha as an institution for astronomy, astrology, mathematics and education and Tusi’s work on writing redactions (Tahiri) or critical editions from various Arabic translations of the Greek classics on mathematics and  geometry. Notably Tusi’s Tahiri al-Majisti (1247), a redaction of Ptolemy’s Almagest, which saw the development of the influential mathematical theorem Tusi Couple as a solution for the problem of Pyolemy’s complicated system of epicycles. The Tusi Couple would have enduring influence throughout the Middle Ages and into the Renaissance where Blake claims it had been adopted by Regiomontanus and Copernicus. Continuing east, the following chapter covers the observatory in Samarqand, Uzbekistan, constructed under the guidance of the astronomer and Timurid prince, Ulugh Beg (1394-1449) which became the largest and most sophisticated observatory in the Eurasian world, carrying out the most advanced observations and analysis. Focusing on the astronomical work of Ulugh Beg, Qadi Zada, Jamshid al-Kashi, and their large team of astronomers and mathematicians. The crowning achievements were the Zij al-Sultani (ca.1440), managing to complete a full 30-year Saturn zodiacal cycle of astronomical observations, it was the most accurate Zij of the period, with calculations said to be more accurate than those of Copernicus or Tycho Brahe. 

The final two chapters on observatories cover the Ottoman empire in the west and the Mughal empire in the east. Blake initially looks at the observatory in Istanbul, built in 1575 and the work of Taqi al-Din (1547-1595) chief astronomer to Murad III. Over the course of seven years of observations, Taqi al-Din completed, the Culmination of Thoughts in the Kingdom of the Rotating Spheres also known as The Emperor's Zij, a groundbreaking work and significant update of the Zij al-Sultani of Ulugh Beg, which was more than 130 years old by mid-1570s. In this chapter Blake relates a story about the sighting of a comet above Istanbul in 1577 on the first night of Ramadan, that was seen throughout the holy month. Following the techniques of mundane (i.e. predictive) astrology, Taqi al-Din interpreted the sighting for an eager Murard III as being an important omen for military implications of the recently initiated campaign against the Safavids in Iran, heralding conquest and peace. The Ottomans were to be victorious over the Safavids at Tiflis early in the following year. However, Blake prefaces this story with the suggestion that the Sultan “had been caught up in the excitement of the Grand Conjunction of Jupiter and Saturn in 1583”, and notes how the Sultan was preoccupied with “occult prognostication” (p.103). Here, Blake demonstrates an underlying disdain for astrology, which is often dismissed as superstitious, with the implication that the astronomers only included astrology for the sake of their gullible patrons to fund their work in astronomy. This undermines the topic of the history of astrology in the Islamic world, and does little to investigate its wider cultural importance.

Continuing with the subject of astrologers, chapter eight looks at the last Muslim dynasty of the Indian subcontinent, the Mughal empire (1526-1739). Here, Blake includes an introduction of the Indic practitioners of astrology (Joytish) whose work continued during the Islamic rule, serving the non-Muslim majority population as well as working within the Islamic households. Noting how under the rule of Akbar I who reigned from 1556 to 1605, the Jyotish practitioners, including the Hindus Muni Sundar and Nilakantha Anata Chintamani and the Jain Padmasundara, were well patronised. Blake states that Nilakantha was the most significant astrologer, serving as the Royal Astrologer (Joytish-Raja), who composed sections on astronomy and astrology for the Todarananda, the vast Sanskrit encyclopedia, and wrote an astrological treatise called Tajikanilakanthi in 1587. However, Blake does not explain the importance of the Tajikanilakanthi, and the cultural syncretism involved in its creation. In which Nilakantha compiled a treatise following the earlier works of Samar Singh and others, on the astrological traditions of the Persians/Arabs who were known as ​​Tajika in Sanskrit. Here, Nilakantha integrated the developments of the Islamicate astrologers into the Jyotish tradition, where Tajika would later become one of the three systems of astrology, alongside the Parāśari and Jaimini systems in modern Vedic Astrology. An important legacy of astrology in the Islamic world. Here readers can refer to Pingree’s From Astral Omens to Astrology (1997), for a more detailed examination of the Tajikanilakanthi.  

Returning to observatories, the later focus of the chapter addresses the last set of observatories in the Islamic world in Shahjahanabad, Jaipur, Varanasi, Mathura and Ujjain, under the Mughal empire, constructed in northern India between 1721 and 1738, for the Mughal Emperor Muhammah Shah (1719–39), under the Rajput ruler, Maharaja Jai Singh (1688–1743). Blake discusses the influence of the European astronomers in the observatories of Jai Singh, who had a small number of Portuguese Jesuits astronomers working at the observatory and completed a scientific mission to Lisbon (1729–31), from which they brought back instruments, books, and tables. However, despite the result of Jai Singh’s observatories, the Zij-i Jadid-i Muhammad Shahi. The concurrent advances in European sciences remained unknown to Jai Singh, and Blake describes it as being “more accurate than the Zij-i Ilkahni or the Zij al Sultani, it was comparatively a medieval geocentric exercise in an early-modern heliocentric world.” (p.122).  

The final chapter looks at the culmination of the influence of the development of the rational sciences upon the Christian west. From the 10th century, translations helped to spread the Islamic works on astronomy and astrology. Scholars produced important and influential translations, such as Adelard of Bath (ca.1080–1150) who produced the first translation of al-Khwarzimi’s Zij (ca.1134), and many Arabic works on astrology and magic. During this period, the Italian, Gerard of Cremona (ca.1114–87) travelled to Toledo where he learned Arabic and translated eighty-seven works of Greek and Islamic astronomy and astrology from Arabic into Latin.  Whilst Al-Majriti’s adaptation of al-Khwarizmi’s Zij al-Sindhind, introducing the Islamic Zij, algebra and Arabic (or Hindu) numbers, the works of al-Zarqali from the Toledo school such as Toldedean Tables, both became widely known throughout western Europe and were adapted for the latitudes of London, Paris and Pisa. Along with the treatises the astrolabe was another Islamic influence brought to European astronomers and astrologers in the 11-12th centuries. Later in the 14th century the Alfonsine Tables were to play an important influence in European astronomy and astrology, cumulating in the work of Regiomonatnus, Copernicus, Brahe and Kepler with a focus on the Observatory of Brahe in Uraniborg Sweden. Blake also gives a summary of the influence of astrology on the philosophers, theologians, and poets of the west, and the effect of the invention of printing in 1454 which “gave birth to an ever-widening interest in astrology. Expanding its reach from the educated elite to the general public” (p.144). 

In his conclusion, Blake seeks to elucidate the popular story of the transmission of the Greek sciences through Arabic translations and into the Latin west and demonstrates the crucial role astronomers and astrologers of the Islamic world played in the development of the rational sciences. Noting the exciting discoveries and advances in astronomy, mathematics and astrology that were achieved in the Islamic world, and their important influence on the astronomers and astrologers of Europe. Blakes summises how their “effort to decipher the riddles of the heavens that spurred the earliest efforts to understand the world in a systemic, proto-scientific manner - to count, model and predict.” (p.146). 

Astronomy and Astrology of the Islamic World, is a tour de force of the developments in astronomy and mathematics, its main focus is on the importance of the observatories and successive developments of the astronomical tables afforded by the increasingly sophisticated technological innovations of astronomical instruments and mathematical developments.  Any student of the history of the Islamic world, or the history of science and mathematics would do well to read this accessible book. One criticism would be on Blake’s treatment of astrology, which is not afforded the level of attention or recognition one would expect from the title.  The strengths of this book lie in the mathematical and scientific journey Blake navigates for us. This is, however, at the expense of the philosophical, cultural and political impact astrology had on the lives of the different cultures in the medieval Islamicate era and beyond. Which brings to life the science of the “judgement of the stars”, through its practical application in the lives of those it served.

Adam Thomas

July 2024