Vir sapiens dominabitur astris: astrological knowledge and practices in the Portuguese medieval court (king João I to king Afonso V)

Abstract

The present study addresses the practice of astrology and its cultural repercussions in the 14th and 15th centuries’ Portuguese court. The research is based in the comparative study of three sets of sources: 1) the astrology books from the royal libraries, which reveal the dominant concepts of astrology; 2) the writings of kings João I and Duarte, and prince Pedro, as examples of the practical application of these concepts; 3) the royal chronicles of Fernão Lopes, Gomes Eanes de Zurara and Rui de Pina, as examples of its presence in political discourse. The astrological references occur in three main contexts: the validation of power, the explanation of manners and the debate about determinism-versus-free will. The latter stands as the main fracturing topic in medieval astrology. In any case, the validity of astrology by itself was never in question; the debate revolved only around its limits and its legitimacy in face of Christian faith. Astrology was seen as a sophisticated art, practiced by learned men. Its foundation was the scientific understanding of the natural laws and its practitioners tried to demarcate themselves from common divination and superstition. Due to its pervasiveness in this period, it can be concluded that astrology is an essential factor for the understanding of Portuguese medieval life. The study of the astrological practice, from the perspective of the History of Culture and Mentalities, offers new insights to the understanding of the medieval period.