The Duke and the Stars: Astrology and Politics in Renaissance Milan
by Monica Azzolini

Reviewed by Mackenzie Anne Cooley

“How much ridicule has been caused by those who, by selling their client an astrological interrogation on some single point, brought him to disastrous end?” mocked the famous mathematician and astrologer Girolamo Cardano (1501 - 1576) as he looked back across the preceding century of Italian history. In this jab, Cardano was not disparaging astrology as a general method of divining the future; rather, he was differentiating his own astrological practice from that of other charlatans who would seek to mislead. Cardano is acclaimed today primarily for his contributions to the history of algebra (especially his pioneering work in the use of negative and imaginary numbers). In life, however, his principal occupation was not mathematician, but astrologer. In Renaissance courts, astrologers served as advisors to rulers, playing an active role in the period’s political decision-making. Using mystical techniques such as horoscopes, interrogations, and elections for guidance on marriage, consummation, travel, and battle, astrologers were employed to ensure both the political success and physical well-being of the duke, his family, and his domain. Much has already been written on astrology, as well as on Renaissance court politics, but Monica Azzolini’s The Duke and the Stars: Astrology and Politics in Renaissance Milan is the first study to examine the influence of astrology on Renaissance statecraft. Azzolini offers an incisive new perspective on how members of the Milanese court utilized astrology in an attempt to control their fates.

Astrology is an ancient method of divination based on the belief that the location of celestial bodies – planets, stars, moon, comets, and constellations – have a direct and significant influence on the course of events here on earth. The study of astrology predates recorded history. To premodern observers, the perfect, circular movements of the stars across the sky seemed different in kind from the chaos of the earthly world. For most of recorded history, and through the period under review, Azzolini notes, the disciplines of astronomy – the study of celestial objects and their mechanics – and astrology “were not thought to be different and irreconcilable, but part of the same realm of knowledge concerned with celestial motion and its effects.” Indeed, “the two Latin terms astrologia and astronomia were used interchangeably.” In the fifteenth and sixteenth centuries, before Galileo and Newton revolutionized understanding of the cosmos, astrology was still a viable theory of nature’s effects on the human world, and it was treated accordingly in Europe’s most powerful courts and prestigious universities. This is crucial to Azzolini’s story: she stresses that astrologers were not simply frauds attempting to dupe dukes who clung to their every word. Rather, they (or some of them at least) were motivated by the genuine desire to understand, and control, the world.

The Duke and the Stars’s strength lies in its focus. It does not attempt to be a comprehensive analysis of early modern astrology, but, rather, it provides a case study of a specific place and time: the Sforza court of fifteenth-century Milan. The Renaissance period was a moment of social innovation and vast political change on the Italian peninsula. The three-estate structure of the medieval period (church, nobility, and peasantry) had diversified; the old social order was crumbling as merchants and bankers, whose finances and power had been growing since the twelfth century, achieved greater political prominence. This new commercial elite employed Italian nobles and others as condottieri, warlords of the mercenary companies contracted by Italian city-states; some particularly successful condottieri, like the Sforza, usurped power and became princes themselves. In fact, the Sforza family name came from the word sforzare, to force. By the period of Azzolini’s study, Milan was one of the glittering cities in Europe. The Sforza dynasty patronized famous architects, military advisors, scholars, and artists, including Leonardo da Vinci.

At the height of the Sforza reign, astrology’s presumed power to predict the future and plan with attention to otherworldly forces made it a key tool for rulers and their courts. “Astrological intelligence” informed both political and medical decisions. Plots abounded when Duke Galeazzo Maria Sforza’s (1444-1476) death was predicted across Northern Italy on the basis of astrological prognostications. Exploiting these predictions in the service of an attempted coup d'etat, three men assassinated him as he attended Mass on 26 December 1476. In the case of Duke Gian Galeazzo Sforza (1469-1494) – a different Duke Galeazzo than the Duke Galeazzo Maria discussed a few sentences ago – Azzolini argues that astrological medicine was both “employed to treat him but also to justify his untimely death.” His physicians timed his treatments to celestial configurations and his natal horoscope. When that failed, his doctors rationalized his demise as “due to his reckless behavior, his poor constitution, and his ill fated nativity.” Historical rumor suggests that what really finished the sickly duke may have been poison from his uncle Ludovico Maria “il Moro” Sforza (1452-1505). Ludovico himself anxiously planned his own physical interactions to match the stars. Following advice from trusted astrologer Antonio Varesi da Rosate, when his bride, Beatrice D’Este, finally came to be of marriageable age at fifteen, he timed both their matrimony and its consummation with alignments in the celestial sphere. To generate a proper prince, it was believed, not only bodies but stars had to be aligned. The Duke and the Stars contributes to a growing trend in the history of early modern science that stresses the extent to which the human world was thought to be interconnected with the environment.

Azzolini draws on an impressive array of archival sources (ducal correspondence, natal charts, and astrological texts, to name a few) to illuminate the overlap between politics and the study of nature in Milanese statecraft. As part of her research, for example, Azzolini provides a close reading of the notebooks of one Giovanni Battista Boerio, a young physician interested in politics and medicine who studied at the University of Pavia - less than a day’s travel from Milan - where astrology was an important part of the curriculum. From Boerio’s careful but partial transcriptions of astrological texts, such as Johannes Sacrobosco’s Computus, Azzolini derives an outline of what the curriculum at Pavia might have been like for a young physician-astrologer in training.

One might think that astrology, the principal predictive art of the duke’s court, began its fall from its “place of pride as a tool of political counsel” during the Italian Wars. When Ludovico at last acquired the imperial investiture of Milan from Holy Roman Emperor Maximilian I, European politics were transfigured beyond the predictions of its astrologers and advisors. King Charles VIII of France died prematurely and Louis XII of Orléans rose to the throne, determined to exercise his perceived legitimate right to the Duchy of Milan. Ludovico’s forces were defeated and France briefly held sway beyond the Alps. The duchy of Milan was conquered and Ludovico, imprisoned; and Spanish rule came temporarily to the Kingdom of Naples. The transformation came quickly. As Milan was converted into a powerful holding of the French and then the Spanish, its arts and sciences diminished without a native dynasty to bolster them. By the 1530s, these events were already being portrayed by Italy’s foremost historian, Francesco Guicciardini, as a cataclysmic turning point that ended a golden era. Despite the loss, and the traumatic conditions of war, Ludovico “maintained his faith in astrology until the very end.” He was not alone. Judging from Girolamo Cardano’s clients, Milanese elites continued to rely on horoscopes long into the sixteenth century. Though the Sforza dynasty came to an end, astrology in Milan did not.