Medical Writers Anonymous On the Nature of Man in Greek

On the Nature of Man is an ancient Greek medical treatise dating from the late fifth or early fourth century BCE. While traditionally ascribed to Polybus, the son-in-law of Hippocrates, modern scholarship regards the work as anonymous. Composed in Ionic Greek, it stands as a foundational text within the Hippocratic Corpus. The treatise is celebrated for its systematic exposition of the theory of the four humors: blood, phlegm, yellow bile, and black bile. It posits that health is a state of equilibrium among these bodily fluids, whereas disease arises from the dominance or deficiency of any one humor. The text elaborates this system by correlating each humor with one of the four cosmic elements—air, fire, earth, and water—and their associated qualities of hot, cold, wet, and dry. It further integrates the theory with the four seasons and the stages of human life, presenting man as a microcosm of the natural order. Structured in ten passages, the work advances this unified physiological theory while explicitly arguing against rival philosophical doctrines that reduced the human constitution to a single substance. Composed during a period of vigorous debate between natural philosophers and medical practitioners, its purpose was to establish medicine on a coherent theoretical basis distinct from abstract speculation. The treatise survives in full through medieval manuscripts transmitted as part of the Hippocratic collection. Its influence was profound and enduring; the humoral theory was later systematized and championed by the physician Galen, becoming the dominant paradigm in Western medicine for nearly two millennia.