All the most acute, most powerful, and most deadly diseases, and those which are most difficult to be understood by the inexperienced, fall upon the … - Hippocrates

Certain s and physicians say that it is not possible for any one to know medicine who does not know what man is, and that who ever would cure men properly, must learn this in the first place. But this saying rather appertains to philosophy, as Empedocles and certain others have described what man in his origin is, and how he first was made and constructed. But I think whatever such has been said or written by sophist or physician concerning nature has less connexion with the art of medicine than with the art of painting. And I think that one cannot know anything certain respecting nature from any other quarter than from medicine... Wherefore it appears to me necessary to every physician to be skilled in nature, and strive to know... what man is in relation to the articles of food and drink, and to his other occupations, and what are the effects of each of them to every one.

The selflessness and dedication shown by many Greek doctors can be seen not only in such works as the Epidemics, but also in, for example, Thucydides’ account of the plague at Athens (II, 47ff.) – where he notes the high incidence of mortality from the disease among the doctors who attempted to treat it.

ἀσκεῖν περὶ τὰ νοσήματα δύο, ὠφελεῖν ἢ μὴ βλάπτειν