Believed illness was caused by an imbalance of a person's Four Humours, not the Gods.
Hippocrates wrote over 70 books however 10 have been lost. He also developed the Theory of the Four Humours, which was one of the few explanations for disease at the time.
CLINICAL OBSERVATION To study a patients symptoms (breathing, temperature) and ask how the illness developed. Make notes and use knowledge of similar cases to predict what will happen next. Once predictions are shown to be accurate, diagnose the illness.
Treatments Diet, exercise and rest (preferably)
Hippocrates believed a doctor should respect all life, and if a doctor did not know how to treat their patient they should not try anything harmful.
The Hippocratic Oath is still used today.