Very little is known of the life of Hippocrates except that he was born on the Greek island of Cos. The main source, Soranus, dates from the second century ad and was clearly telling a traditional tale rather than writing a biography. Hippocrates is reported to have studied under his father Heraclides, also a physician, and with the atomist Democritus, and the sophist Gorgias. He then seems to have spent most of his life traveling around the Greek world curing the great of obscure diseases and ridding grateful cities of plagues and pestilence.

After the fantasy of his life there is the reality of the Corpus Hippocraticum (The Hippocratic Collection). This consists of some 70 works though whether any were actually written by Hippocrates himself will probably always remain a matter of speculation. What is clear, on stylistic and paleographic grounds, is that the corpus was produced by many hands in the second half of the fifth century and the first part of the fourth. Nor do the works represent a single ‘Hippocratic’ point of view but, it has been suggested, probably formed the library of a physician and acquired the name of its first owner or collector.

Of more importance is the character of these remarkable works. They are surprisingly free of any attempt to explain disease in theological, astrological, diabolic, or any other spiritual terms. Diseases in the Corpus are natural events, which arise in a normal manner from the food one has eaten or some such factor as the weather. The cause of the disease is for the Hippocratic basically a malfunction of the veins leading to the brain which, though no doubt false, is the same kind of rational, material, and verifiable claim that could be found in any late 20th-century neurological textbook.

Such rationality was not to rule for many years for in the fourth century bc new cults entered Greece and with them the dream, the charm, and other such superstitions entered medicine. More successful in the length of its survival was the actual theory of disease contained in the Corpus. This was the view, first formulated by Alcmaeon in the fifth century bc, that health consists of an isonomia or equal rule of the bodily elements rather than a monarchia or domination by a single element. By the time of Hippocrates it was accepted that there were just four elements, earth, air, fire, and water with their corresponding qualities, coldness, dryness, heat, and wetness. If present in the human body in the right amounts in the right places health resulted, but if equilibrium was destroyed then so too was health.

A new terminology developed to describe such pathological conditions, a terminology still apparent in most western languages. Thus an excess of earth, the cold/dry element, produced an excess of black bile, or in Greek melancholic, in the body; too much water, the cold/moist element, made one phlegmatic.

One striking contrast between Hippocratic and later medicine is the curious yet impressive reluctance of the former to attempt cures for various disorders: the emphasis is rather on prognosis. For example, the Epidemics describes the course, but not treatment, of various complaints. At least knowing the expected course and outcome of an illness helped the practitioner to inform his patient what to expect, information that could be useful and reassuring. Further, if it is known which conditions lead to a disease such conditions could sometimes be avoided.

The works Regimen in Acute Diseases and Regimen in Health, which deal specifically with therapy, tend to restrict themselves to diet, exercise, bathing, and emetics. Thus the Hippocratic doctor may not have cured many of his patients but he was certainly less likely than his 18th-century counterpart to actually kill them.