Empires and exact sciences in pre-modern Eurasia

 

29-30 May 2006Leiden, the Netherlands

 

The seminar ‘Empires and Exact Sciences in Pre-modern Eurasia' was held in Leiden, 29-30 May 2006, in memory of one of the 20th century's leading scholars of the cross-cultural development of pre-modern science, David Pingree. It was sponsored by CNWS, Brill Academic Publishers and IIAS. The proceedings will be published in a forthcoming issue of the journal East and West of the Istituto Italiano per l'Africa e l'Oriente in Rome.

Kim Plofker

Pre-modern Asia's diverse intellectual traditions shared a scientific enterprise in the development of mathematical astronomy and astrology. Inspired by the prospect of foretelling the future, and by the mathematical beauty of heavenly motions, scholars in the dominant cultures of Asia and Europe constructed a remarkably complex system of calculation, observation and prediction that became the springboard for modern physical science.

The global diffusion of scientific ideas is sometimes regarded as an exclusively modern phenomenon; but the ancient and medieval history of science in Europe and Asia, where imperial power often served as the transmission vector for scientific theories, contradicts this notion.

Reading the future in the skies

It may startle the modern reader to see astrology lumped with mathematics and astronomy under the name ‘science'. Astrology has been excluded from that status by the modern definition of scientific method and is nowadays decisively classed as a pseudoscience. However, in earlier times it was considered one of the standard quantitative systems for understanding the physical world - the so-called ‘exact sciences' - and most mathematicians and astronomers were astrologers as well.

The Babylonians of the early second millennium BCE believed that certain celestial phenomena such as eclipses and conjunctions of planets were messages from the gods to the rulers of humanity, warning them of crises and trials to come. This belief persisted even as Babylonian scribes grew more skilled at describing the periodic recurrences of such phenomena mathematically. Even when sophisticated late Babylonian mathematical astronomy had made the apparent cycles of the heavens almost completely predictable, astronomers still took their ominous significance very seriously.

But by then Mesopotamia was under the control of the Persian and Macedonian empires, who took little interest in celestial warnings from Babylonian deities. So the astronomers turned to forecasting the future for individual patrons rather than for the state. They appear to have invented the concept of the horoscope, a prediction of the fate of an individual based on the positions of the stars and planets at the moment of his or her birth. The allure of such glimpses into the future launched the disciplines of mathematical astronomy and astrology on their far-flung wanderings through the subsequent millennia.

Dissemination of exact sciences

Greek scholars encountered Babylonian astronomy and celestial omens in Ptolemaic Egypt in the second half of the first millennium BCE. They superimposed the spherical cosmology of their own philosophical systems onto some of the Babylonian algorithmic schemes for mathematically predicting astronomical phenomena. This combination developed over the next few centuries into the famous system of nested celestial spheres, all revolving around a stationary spherical earth, that we know as ‘Ptolemaic' astronomy.

The geometrised Ptolemaic universe served as the model for probably the most important scientific instrument of pre-modern times, the plane astrolabe (see sidebar). Greek science also adopted Babylonian ‘proto-horoscopes' and expanded them into a full-blown system of horoscopic astrology.

In the flourishing trade of the Roman empire in the early first millennium CE, the Hellenistic exact sciences spread eastward to India, where they developed into the astrology and spherical astronomy of the classical Sanskrit tradition. These Indian sciences then rippled outward to enrich the astral knowledge of cultures in pre-Islamic Iran, China and Southeast Asia.

The complex multi-cultural layering of such knowledge is illustrated in Figure 1, which shows the iconography of the zodiacal signs Virgo and Pisces as represented in a mandala in the Toji temple in Kyoto. Here we see Japanese versions of Chinese versions of Indian versions of the signs of the celestial zodiac adapted by Greeks from its original Babylonian form. (Note that in the process the single maiden representing the sign Virgo has become two, and the two fish representing Pisces have become one.)

The rise and expansion of Islam in the 7th century continued the development and transmission of the exact sciences. In addition to many influences from India and Sassanian Iran (such as the decimal place-value numerals and various mathematical, astronomical and astrological methods), science in the Islamic world incorporated the Hellenistic Greek theories of ancient authors such as Euclid, Archimedes and Ptolemy. Embodied mostly in Arabic and Persian texts, these new syntheses of mathematical astronomy and astrology were carried to India, Central Asia, China, Byzantium and the Latin West. There they came into contact with different versions of the exact-sciences tradition, sometimes stimulating efforts by scientists to compare, assess and reconcile their variants.

Figure 2 shows an example of one of these second millennium cross-cultural transmissions: an Arabic manuscript, written in India, explains the cosmology of nested heavenly spheres derived ultimately from Greek philosophy. In the western world, such interactions between variant traditions helped form the Renaissance science that eventually replaced the Ptolemaic systems of astronomy and astrology with the heliocentric cosmos of early modern astronomers like Copernicus, Kepler and Newton.

Bibliography

- Burnett, Charles et al. 2004. Studies in the History of the Exact Sciences in Honour of David Pingree. Leiden: Brill.

- Pingree, David. 1997. From Astral Omens to Astrology, from Babylon to Rome. Rome: Istituto Italiano per l'Africa e l'Oriente.

- Yano, Michio. 2004. Hoshi-uranai no Bunka-koryu-shi (Historical Accounts of Cultural Exchanges in Astrology). Tokyo: Keiso Shobo.

Kim Plofker just completed a two-year fellowship at the Mathematics Institute of the University of Utrecht and IIAS. Her book on the history of mathematical sciences in India is forthcoming from Princeton University Press.

Kim_Plofker@alumni.brown.edu