Hippocrates (c. 460–c. 377 BC)

Greek physician, often called the founder of medicine. Important Hippocratic ideas include cleanliness (for patients and physicians), moderation in eating and drinking, letting nature take its course, and living where the air is good. He believed that health was the result of the 'humours' of the body being in balance; imbalance caused disease. These ideas were later adopted by Galen.

He was born and practised on the island of Kos, where he founded a medical school. He travelled throughout Greece and Asia Minor, and died in Larisa, Thessaly. He is known to have discovered aspirin in willow bark. The Corpus Hippocraticum/Hippocratic Collection, a group of some 70 works, is attributed to him but was probably not written by him, although the works outline his approach to medicine. They include Aphorisms and the Hippocratic Oath, which embodies the essence of medical ethics.

The Corpus Hippocraticum remains impressive for its focus on observation and the description of symptoms. Diseases are seen as being caused by an imbalance of the four basic ingredients, or humours, of the human body (blood, phlegm, yellow bile, and black bile). This remarkably influential idea perhaps gained credence by analogy with the theory of the four elements of matter of Zeno of Elea and Parmenides. Being vague, the theory of humours was also widely applicable, for instance in its link with the seasons (winter illnesses being characterized by cold and wet discharges). Where given, the treatment suggested consists of eating compensatory food such as hot and dry foods in winter. The Hippocratic tradition in medicine remained dormant until the 18th–19th century, when it was replaced by the germ theory of disease, but the image of Hippocrates as the ideal physician remains today.


Galen (c. 129–c. 200)

Greek physician and anatomist whose ideas dominated Western medicine for almost 1,500 years. Central to his thinking were the theories of humours and the threefold circulation of the blood. He remained the highest medical authority until Andreas Vesalius and William Harvey exposed the fundamental errors of his system.

Galen postulated a circulation system in which the liver produced the natural spirit, the heart the vital spirit, and the brain the animal spirit. He also wrote about philosophy and believed that Nature expressed a divine purpose, a belief that became increasingly popular with the rise of Christianity (Galen himself was not a Christian). This helped to account for the enormous influence of his ideas.

Galen was born in Pergamum in Asia Minor and studied medicine there and at Smyrna (now Izmir), Corinth in Greece, and Alexandria in Egypt, after which he returned home to become chief physician to the gladiators at Pergamum. In 161 he went to Rome, where he became a society physician and attended the Roman emperor Marcus Aurelius Antoninus. Although Galen made relatively few discoveries and relied heavily on the teachings of Hippocrates, he wrote a large number of books, more than 100 of which are known.


The dissection of human beings was then regarded as taboo and Galen made inferences about human anatomy from his many dissections animals. His detailed descriptions of bones and muscles, many of which he was the first to identify, are particularly good; he also noted that many muscles are arranged in antagonistic pairs. In addition he performed several vivisection experiments; for example, to show that urine passes from the kidneys down the ureters to the bladder. More important, he demonstrated that arteries carry blood, not air, thus disproving Erasistratus' view, which had been taught for some 500 years.