A Kingdom of Stargazers: Astrology and Authority in the Late Medieval Crown of Aragon by Michael A. Ryan (review)

Astrology has long enjoyed or endured an uneasy relationship to princely authority. On the one hand, princes often condemned astrological practice and censured astrologers, at least officially. On the other, those same princes typically consulted astrologers on matters ranging from personal health to military campaigns. Michael Ryan’s A Kingdom of Stargazers examines three Aragonese courts to understand how a prince’s enthusiasm for or rejection of astrology could confirm or undermine his authority.

The first half of Ryan’s book surveys medieval arguments for and against astrology. Aligned against astrology and divination is a mix of usual suspects along with some geographically specific authors: Augustine, Aquinas, William of Auvergne, John of Salisbury, and Anselm Turmeda. On the other side, Roger Bacon and King Alfonso X supported astrology, at least when practiced at princely courts by authoritative experts. Ryan finds medieval opposition to have largely won the argument, until the fourteenth and fifteenth centuries, when rulers found in astrology means of understanding or at least coping with a series of profound crises, including the Black Death and the Great Schism.

Ryan’s real contribution comes in his careful analysis of astrology at the Aragonese courts of Pere the Ceremonious (1336–87), Joan the Hunter (1387–96), and Martí the Humane (1396–1410). Although each monarch was anxious about the future, each also worried about the legitimacy of divining that future. Court politics, courtly fashion, and religious orthodoxy shaped the monarch’s approval or rejection of astrology. Monarchical authority, in turn, influenced contemporary opinions about the monarch and his relationship to astrology. Pere the Ceromonius was a strong ruler who drew on traditional markers of authority, especially military might, moral rectitude, and patronage of the arts and science. In his own Crònica, Pere celebrated his patronage of astrologers and astrology. He encouraged his physician and administrators to study the stars and had his astrologers produce new astronomical tables. Joan the Hunter, by contrast, lacked traditional symbols of princely authority. He was more interested in French courtly pastimes, such as music, hunting, fashion, and astrology than in governing his kingdom. Contemporary accounts, especially those by court scribe Bernat Metge and the inquisitor Nicolau Eymerich, denounced Joan and his interest in astrology. Martí the Humane was the most orthodox and fiscally conservative of the three monarchs. Despite inheriting numerous astrological texts and showing early interest in alchemy, once he ascended the throne he eschewed efforts to foresee the future. He strove to distinguish his conservative court from the extravagance of Joan’s rule.

In each case, the ruler’s perceived authority transferred to astrology, which, in turn, bolstered or undermined the king’s rule. Pere, a strong monarch, could use astrology to support his efforts to consolidate his power. In his hands, astrology became another symbol of his authority. Joan was a weak monarch whose interest in astrology was taken as further evidence that he was a bad ruler. Martí defined himself against his immediate predecessor. Whereas astrology had played an important if detrimental role in Joan’s rule, under Martí astrology lost its role in constructing his authority. What emerges from Ryan’s study is the equivocal nature of astrology. Astrology per se was not authoritative. Rather, astrology reflected the monarch’s authority, or suffered from the monarch’s weakness.

I want to use A Kingdom of Stargazers to raise a few thorny methodological issues. Perhaps most challenging: How do we distinguish between astrology, divination, magic, occult practices, prophecy, and the many other slippery terms historians typically use when studying astrology? In his analysis Ryan tries to navigate these divisions. His task is made more difficult by the sources, which slip from one term to another or elide possible distinctions between practices. What characterized an effort to foresee the future as licit or illicit...