Overview

After philosophers such as Aristotle and Plato decided that the human body was not needed in the afterlife, Greek doctors at Alexandria in Egypt began to dissect bodies. Some even dissected the bodies of criminals who were still alive (vivisection). In this way the surgeon Herophilus realised that the brain, not the heart, controls the movement of the limbs, and Erasistratus discovered that the blood moves through the veins (although he did not realise that it circulated). Thus the Greeks began to find out in a systematic way about the inside of the body.

Based on their observation of life, Greek philosophers such as Thucydides realised that prayers were useless against illnesses such as the plague, and that epilepsy was not caused by the gods. Hippocrates's book 'Airs, Waters and Places' suggested that disease was caused by the environment. Thus the way was open for an entirely natural theory of the cause of disease.

Based on the theory that natural matter comprised four basic elements, the Greek philosophers came up with the idea that the human body consisted of the four humours [Four humours: Four bodily fluids - yellow bile, black bile, blood and phlegm - used in ancient times to analyse and describe people's state of health. ], which had to be kept in balance. This theory survived until after AD 1700.

The 'four humours' that Greek doctors used as a basis for medical diagnoses

Then, derived from his study of mathematics, the Greek philosopher Pythagoras came up with the idea of the balance of opposites. This gave Greek doctors their idea of the underlying cause of disease. We can read about this in the 70 books ascribed to the Greek doctor Hippocrates, who thought that disease occurred when the humours of the body fell out of balance.

Greek doctors made careful studies of the different kinds of illness - in particular they noted the natural history of the illness.