Hippocrates, rightly considered the ‘father of rational medicine’, was a Greek physician who lived on Cos — an island off the coast of present-day Turkey.

Prior to Hippocrates, medicine in Greece (not to mention the rest of the world) was steeped in religious belief. Illness would automatically be attributed to the activities of gods or demons, and treatment depended heavily upon praying, exorcism, and giving gifts to the gods. Treatments based on physical causes were unlikely to be developed by physicians in this frame of mind.

Hippocrates and the school he founded set about freeing ancient Greece of the shackles of medical supernaturalism. Careful observation, interviewing of patients, and recording of results became the mainstays of medicine.

Under the Hippocratic method, theorizing centered on material processes rather than ethereal ones. This was an improvement, but no guarantee against the development of nonsense theories. For example, European medicine clung to the utterly wrong theory of the Four Humors from the time of Hippocrates until the 17th Century.

Hippocrates advocated good diet and exercise as an essential part of medical treatment. He considered cooked foods and processed foods to be superior to raw, unmixed, or ‘natural’ foods, since the latter were more likely to contain substances that cause or promote illness. The diet-and-exercise aspect of Hippocratic medicine was soon forgotten and has yet to be fully appreciated to this day.