Is it possible to apprehend man from a medical standpoint without offering a purely materialistic definition ? Such was the question raised by Italian physicians at the end of the Middle Ages when they developed a full scale theory of the idea of complexion, which they saw as a "substantial quality" specific to man, but one that also depended on hereditary traits, food, age, or even climate and mores. Practicing their art, some of these physicians could thus contemplate improving not simply the health, but also the well being of each individual.