Astrology and Astronomy in the Court Culture of the Avis Dynasty

This chapter discusses the role of astrology in the court culture of the Avis Dynasty. Astrology was widely practised and reflected a court culture where it played a significant role in decision-making and understanding the world. Philippa of Lancaster likely encountered astrology at a young age, given her connection to Geoffrey Chaucer, who was known to incorporate astrological references in his writings and may have practised it himself. In Portuguese court culture, astrology was practised mainly by learned Jewish men. Court astrologers like Moses ben Abraham of Leiria, a physician to King João I, wrote a treatise on the astrological determination of lifespan, showcasing the high level of erudition required in astrological practice. João I mentioned astrology in his book on hunting, whereas Duarte and Pedro (his sons with Philippa) both wrote about astrology, the former debating its implications for free will and determinism, and using astrology, for example, to determine auspicious times for ceremonies.

Luís Campos Ribeiro, Helena Avelar de Carvalho, and Samuel Gessner, “Astrology and Astronomy in the Court Culture of the Avis Dynasty,” in Philippa of Lancaster and the Court Culture of Medieval Portugal, ed. Tiago Viúla De Faria, The New Middle Ages (Cham: Springer Nature Switzerland, 2025)