After over two years of living in a pandemic, most everyone is familiar with COVID-19’s periods of incubation, progression and contagion. Governments and doctors have used the regularity of its phases to establish protocols for quarantines, testing, and sick leaves. We are all well aware that disease is transmitted through the air. Similar issues were of great concern to physicians in early modern Europe. They noted the periodicity of diseases, especially of recurring fevers, referring to pivotal points as crises or critical days. Some early modern physicians blamed the air for epidemics, assuming that diseases that afflict many people must be caused by a commonly shared element.

Early modern physicians weighed several explanations for these characteristics of disease. Possible causes included celestial bodies. Fevers’ cycles might be linked to the phases of the moon. Pestilential air might be caused by astral influences. Consideration of astral influences on disease had a lengthy history, going back to antiquity. Medieval astrologers developed elaborate systems that took into account planetary conjunctions and the zodiac.

Many professors in early modern universities taught these astral theories of disease, but controversies arose in Padua at the turn of the seventeenth century. At the time, Padua was Venice’s university and home to one of Europe’s most important medical schools. Students at Padua often learned in a hands-on manner in clinics, the anatomy theatre and botanical garden. Professors emphasized the importance of direct observation. The university was also a center for studies on Aristotle, whose writings provided philosophical foundations for medical theory.

The emphases on direct experience and Aristotle’s writing contributed to rising doubts about astral causes. Although astrologers had for centuries invoked Aristotle, several philosophers at Padua thought that Aristotle’s thought was incompatible with astrology, because he believed that the heavens are made of ether, an unchanging, eternal matter that could possess neither active powers like heat and cold nor moral qualities like good and evil. Physicians noticed that the timing of fevers often did not match up with lunar phases and that recent outbreaks of plague could not be easily attributed to air affected by astral powers. Several professors at Padua not only dropped astrology from their teachings but also polemicized against it.

During these years, Venice, which governed Padua’s university, was politically divided. Disagreements grew about whether the Republic should be allied with the papacy or independent from it. Many of the professors who doubted astrology were linked to the anti-papal faction. In the 1620s, Venice faced riots and a constitutional crisis. As the pro-papal faction ascended in power, the new government increasingly favored antagonists to those professors who had supported the anti-papal faction and polemicized against astrology. By 1630, the teaching of astral medicine was refurbished. In early modern Europe, medicine was frequently mired in politics, something that is also familiar to all of us today.

Read Craig Martin’s full open access article Medicine and the heavens in Padua’s Faculty of Arts, 1570–1630 on Cambridge Core now.