Modern medicine has grown by means of a tradition that is almost 2,400 years old. Its practices are said to have begun on the Greek island of Cos, near the western coast of Asia Minor, where a school arose around the teachings of the legendary Hippocrates. Today the name of Hippocrates is mentioned most frequently in discussions of the oath attributed to him. But the Hippocratic physicians did far more than introduce the principles from which the codes of today's medical ethics have developed.

Perhaps the single most striking difference between the doctors of the Hippocratic school and all others was their injunction that the causes of disease should no longer be attributed to the influence of supernatural forces. Henceforth, the origins of illness were to be sought in observable natural factors that influence the functions of the body. Attempts were made to relate specific symptoms to actual internal or environmental causes, rather than to the intervention of displeased and vengeful gods. This was a departure for physicians accustomed to seeking cures by appealing to the divinities with prayer and sacrifice.

Casting off the shroud of mysticism, the Greek physicians replaced it with the thesis that the causes and cures of every disease are not only quite natural but also discoverable through the careful study of each patient. Thus curiosity, keenness of observation and the value of scrupulous record keeping became paramount priorities in the new philosophy of care. And as knowledge grew and was shared within the guild, the experience of a single physician became the experience of all.

Over the course of several hundred years, a literature, later known as the Hippocratic Corpus, was created, forming the basis of all medical practice. Since that , the accumulated and recorded knowledge of one generation has been passed on to the next through literature and via those who teach their successors. Docere, the Latin word from which the word doctor is derived, means "to teach."