On Medicine (De Re Medica)

...Hippocrates of Cos: he was indeed the first of all worthy of memory to separate this discipline from the study of wisdom, a man distinguished both in art and in eloquence. After him, Diocles of Carystus, then Praxagoras and Chrysippus, then Herophilus and Erasistratus, practiced this art in such a way that they even progressed into different methods of healing.

In those same times, medicine was divided into three parts: one that healed through dietetics regulated food and lifestyle, another through pharmaceutics medicine/drugs, and a third through surgery manual intervention. The Greeks named the first diaetetice, the second pharmaceutice, and the third chirurgia. However, the authors most famous for that which heals diseases through diet also attempted to address deeper matters, and claimed for themselves the knowledge of the nature of things as well, as if medicine would be maimed and weak without it. After them, Serapion was the first of all to profess that this rational discipline had nothing to do with medicine, and he placed it in usage and experiments alone. Apollonius and Glaucias, and somewhat later Heraclides of Tarentum, and other men of no small standing followed him, calling themselves Empirici Empiricists from their very profession. Thus, the part of medicine that heals through diet was also divided into two parts, with some claiming for themselves the rational art, and others only usage; and no one after those who have been mentioned above stirred anything other than what he had already received, until Asclepiades changed the method of healing to a great extent; and among his successors, Themison himself recently altered certain things in his old age. And it is through these men, above all, that this salutary profession of ours has grown.