Cardano's Cosmos: The Worlds and Works of a Renaissance Astrologer (review)

Cardano's Cosmos: The Worlds and Works of a Renaissance Astrologer by Anthony Grafton. Harvard Univ. Press, Cambridge, MA, U.S.A., 1999. 284 pp., illus. ISBN: 0-674-09555-3.

Girolamo Cardano (1501-1576) is well-known among historians of medicine as a famous physician who worked in Milan and later in Pavia and Bologna; he was apparently second only to Vesalius among European doctors. Historians of mathematics know him for his work in solving cubic equations (along with Niccolo Tartaglia); students still learn "Cardano's Rule." He also made contributions to the burgeoning subject of probability, showing that more than luck is involved in games, namely statistical rules, and he explored elements of mechanics, hydrodynamics and geology. He truly was, in the lay sense, a "Renaissance man."

But almost none of this is to be found in this book, simply because Grafton focuses on astrology, not science. Of course, this modern distinction was not part of the sixteenth-century worldview. Hence physicians often relied on the stars in their diagnoses; this was based on the belief that the sun, moon and planets influence the four humors in the body. So Grafton does not ignore, although the discussion is minimal, the medical side of Cardano's life. Moreover, large-scale predictions of famine and death were expected of these physician-astrologers. Much of the physical sciences were also bound-up with what was called "natural magic," a probing of occult forces (such as magnetism) inherent in nature; hence we find even Newton in the seventeenth century speaking of gravity as a power extending throughout space. Grafton only touches on "natural magic." Finally no one but the careful reader would know that Cardano explored mathematics at all (Tartaglia, for example, is not mentioned); the only reference I found is a passing comment on Cardano's mathematical work in connection with his idea that dreams play a role in making discoveries (p. 165).

Thus, this book looks primarily at one side of Cardano's life--to be sure, as he saw and lived it, an important part--that of a Renaissance astrologer. As such, this facet of his life is at times fascinating but often tedious in the day-to-day perils. There was cutthroat competition among astrologers as they attacked each other about their relative predictive powers. Grafton can be a wise and clever writer, and his asides--making parallel references to aspects of society today--are often quite amusing, if not insightful. Thus the modern parallel to the astrologer's predictive competition may be found in commercials and advertisements among mutual fund companies. Related to this, I particularly like the following analogy between the social role of ancient and Renaissance astrologers and modern economists:

At the most abstract level, astrologers ancient and early modern carried out the tasks that twentieth-century society assigns to the economist. Like the economist, the astrologer tried to bring the chaotic phenomena of everyday life into order by fitting them to sharply defined quantitative models. Like the economist, the astrologer insisted, when teaching or writing for professional peers, that astrology had only a limited ability to predict the futures. Like the economist, the astrologer generally found that the events did not match the prediction; and like the economist, the astrologer normally received as a reward for the confirmation of the powers of his art a better job and higher salary (p. 10).

On the predictive power of astrology, Cardano was not a strict determinist; he believed that the stars set limits to one's life, but otherwise both environmental factors and individual choice set one's fate.

Cardano's astrological career put him in contact with a wide range of intellectuals and religious leaders. Historians of science will recognize some familiar names here as Cardano rubs shoulders with Andreas Osiander and Rheticus. Students of the Reformation will learn that while Melanchthon was fascinated with astrology, Luther was repelled. And those of us who read at...