Heavenly Measures: Medieval Approaches to Cosmology, Astronomy, and Astrology

This course explores the evolution of the scientia stellarum—the “science of the stars,” encompassing both astronomy and astrology—throughout the Middle Ages. It traces the diverse approaches to these disciplines over the longue durée, with particular emphasis on practices, innovations, paradigm shifts, and the changing role of the sciences in medieval culture. A particular focus will be placed on the transformative influence of Arabic astronomy and astrology on medieval Europe. The transmission and translation of scientific works from the Islamic world not only revitalized but also fundamentally reshaped Western approaches to the study of the heavens. These developments will be examined in relation to the complex interplay between astronomy and astrology, as well as their intersections with other fields of knowledge, particularly medicine. The course will also consider the articulation between theory and practice in the teaching of the scientia stellarum, one of the four disciplines of the quadrivium. Although taught within the liberal arts, astronomy and astrology were not associated with professional roles in the modern sense. This raises important questions of identity: who practiced these sciences, and in which intellectual, religious, or social contexts? Medieval debates surrounding astrology, particularly its theological legitimacy and epistemological boundaries, will form a central theme. The course begins with an introduction to medieval cosmology, rooted in ancient traditions and reshaped through the assimilation of science from the Islamic world. It will examine the varying relationships between astronomy and astrology, the methods of learning and practicing the scientia stellarum, and conclude with the study of almanacs and ephemerides — tools that facilitated astronomical and astrological work and marked the early stages of the professionalization of the astrologer. Designed as an introduction to medieval science, the course will engage students directly with primary sources and material culture.  

Each session will include a study of primary sources, including astronomical and astrological manuscripts and instruments on display. This will underline the importance of palaeography, philology and codicology in the construction of historical knowledge, especially in the history of medieval science. Sessions will be held in the Weston Library to explore medieval scientific manuscripts, and at Merton College and the History of Science Museum to study a range of astronomical instruments, including astrolabes, equatoria, and armillary spheres.