Approaches to the Critical Days in Late Medieval and Renaissance Thinkers

Galen's astrological doctrine of the critical days, as found in his De diebus decretoriis (Critical Days), Book III, was at the center of a long discussion in the Latin West about the relationship between astrology and medicine. The main problem was that Galen's views could not be made to square with the prevailing cosmology, which derived both from Aristotle and Abu Ma'shar. The views of selected Latin thinkers concerning the critical days, from Pietro d'Abano, down through Girolamo Cardano, are considered in the context of a fourfold scheme that aims to classify the main approaches to the critical days. The criticisms of Pico della Mirandola are discussed, as well as two kinds of responses to him: the progressive views of Giovanni Mainardi and Girolamo Fracastoro, as well as the conservative views of Thomas Bodier and Girolamo Cardano.