Humoralism and Adam's Body: Twelfth-Century Debates and Petrus Alfonsi's Dialogus contra Judaeos

Many twelfth-century Christian theologians reexamined original sin and its corrupting influence upon the soul. At the same time, some theologians investigated the consequences of Adam’s sin for the human body, considered as a proper subject for natural science in general and medicine in particular. This latter discussion applied medical concepts from Galenic humoralism to determine that, in addition to the corruption introduced to the soul, Adam’s sin also resulted in an imbalance in the humoral complexion of the human body. This imbalance will be treated as the root cause of all illness and disease and, ultimately, the reason for the death of the body. This paper shows that Petrus Alfonsi’s Dialogue against the Jews provides an important early twelfth-century source for this discussion (which will expand greatly in the thirteenth century) and one which served as a conduit too for medical and scientific knowledge mediated by Arab culture.