Astrology and Cosmology

Abstract

This chapter argues that Ptolemy maintains the epistemology and scientific method that he articulates in Almagest 1.1 and applies in the Harmonics in his studies of astrology and cosmology in the Tetrabiblos and Planetary Hypotheses. Both Ptolemy's astrology and his cosmology rely on astronomy. Indeed, Ptolemy suggests that their very study depends on an antecedent and complete examination of the stars' movements and configurations. The conclusions astrology and cosmology put forward, however, remain conjectural, and Ptolemy remarks in both the Tetrabiblos and Planetary Hypotheses on the conjectural nature of astrology, cosmology, and physics in general. Nevertheless, by placing his astrology and cosmology on an astronomical foundation, Ptolemy endeavours to produce the best guesses possible of the physical characteristics of aethereal bodies and the physical effects they have on the sublunary realm.