From Critical Days to Critical Hours: Galenic Refinements of Hippocratic Models

This paper addresses the questions of when, why, and to what degree ancient physicians concerned themselves with temporal precision. Taking On Critical Days as a case study, it explores how Galen of Pergamum incorporates hourly timekeeping into his defense and refinement of Hippocratic "critical-day" schemes, designed to help physicians anticipate turning-points in febrile diseases. The paper proposes that Galen, in both his fever case histories and his astronomical explanations for critical days, uses hourly timekeeping to support certain claims about himself, his medical methodology, and the authority of Hippocrates.