Whoever wishes to investigate medicine should proceed thus: In the first place, consider the seasons of the year and what effect each of them produces.
HippocratesFirst of all a natural talent is required; for when Nature opposes, everything else is in vain; but when Nature leads the way to what is most excellent, instruction in the art takes place.
HippocratesThe human body contains blood, phlegm, yellow bile and black bile. These are the things that make up its constitution and cause its pain and health. Health is primarily that state in which these constituent substances are in the correct proportion to each other, both in strength and quantity, and are well mixed.
Hippocrates