Introduction

Galen (d. c. A.D. 216) is well-known as an anatomist, physiologist, therapist, and medical theorist. He is less known as one of the founders of medical astrology, through the inuence of the Critical Days.1 Leaving astrology aside, it is noteworthy that Galen laid the foundations of a theory of medical prognosis, via the pulse and the medical crises, which endured in medical practice for most of two millennia. Neither have been extensively studied, and the latter hardly at all.2