Although always a part of philosophy, psychology has close ties as well to biology, especially human physiology and medicine. As long as the mind is in some way attached to a body, this is inevitable. But, as you know, it took quite a bit of prying the mind apart from its religious connection with an immortal soul before that intimate connection would be acknowledged!

“The First Physician,” at least as far as the Greeks were concerned, was Asclepius. He started a partially mystical society or guild of physicians that was to have an influence for many centuries to come. During that time, he gained god-like status. Even Socrates, as he lay dying of the overdose of hemlock, told his student Crito to sacrifice a cock to Asclepius, presumably in thanks for an easy death.

More clearly historical is Acmaeon of Croton (b. 435 bc) in southern Italy. A pythagorean by philosophy, he was known for his anatomical studies. He is the first person we have record of who dissected the eye and discovered the optic nerve. His theory of the mind included the idea that the brain is the seat of perception and thought, and that there are connections from all the sense organs to the brain. He believed that it was pneuma, meaning breath or animal spirits, ran through the body like neural signals.

Disease, he theorized, is at least in part due to a loss of balance in the body. He postulated a set of opposites, especially hot and cold, wet and dry, and bitter and sweet, that we need to balance in order to maintain health, by controlling our temperature, nutrition, and so on.

Hippocrates (b. 460 bc) of Cos in Asia Minor, is better known. He was an Asclepiad -- i.e. a member of the medical guild, and is the originator of the Hippocratic Oath (click here to read it. But note: Contrary to popular belief, few if any doctors are required to take this or any other oath!). Despite his background, he preferred to avoid mystical interpretations and stick close to the empirical evidence. For example, in a treatise called “On the sacred disease” (meaning epilepsy), he dismissed the usual demonic-possession theory and suggested that it was an hereditary disease of the brain.

He is also known for his theory of humors. According to Greek tradition, there are four basic substances: earth, water, air, and fire. Each of these has a corresponding “humor” or biological liquid in the body: black bile, phlegm, blood, and yellow bile, in that order.

These humors, just like the four basic substances, vary along two dimensions: hot or cold, and wet or dry, like this...

Like Alcmaeon said, the task of the physician is to restore balance when the relative proportions of these humors were out of balance. Hippocrates also noted some emotional connections to these humors.

It should be noted, despite the odd humor theory, that Hippocrates and with him Plato correctly recognized the significance of the brain. A bit later, around 280 bc, Erasistratus of Chios dissected the brain and differentiated the various parts.

For the most part, of course, medicine in these centuries, and for many centuries to come, consisted of a blend of first aid -- the setting of bones, for example -- and herbal remedies, plus a considerable amount of praying to the gods for miraculous intervention! (For a brief history of psychopharmacology from ancient times to the present, click here.)

In the Roman Empire, another physician gained fame that would last well into the Middle Ages: Galen was born 130 ad in Pergamon in Asia Minor -- a major center of learning at the time. He went to Alexandria -- THE center of learning -- to study anatomy. In the Roman Empire, dissection of humans was not allowed -- based, of course, on superstitious fear of retribution, not on any feelings of human dignity! So Galen studied the great apes instead.

At the age of 28, he returned home for a while to serve as surgeon to the gladiators. His fame spread, and he went to Rome.

In addition to a great deal of fairly decent, concrete advice, he theorized that all life is based on pneuma or spirit. Plants had natural spirit, which causes growth. Animals have vital spirit, which is responsible for movement. And human beings have animal spirit -- from the word anima, meaning soul -- which is responsible for thought.

He believed that cerebrospinal fluid was the animal spirit, and noted that it was to be found in the cerebral vesicles of the brain as well as the spinal cord. He believed it traveled out through the nerves to the muscles, as well as in from the sensory organs. Not bad.

It was Galen who added the idea of temperaments to Hippocrates’ four humors:

Note how these words have come down to us. Note also how we use terms like “he is in a good humor,” “he has a bad temper” (as in temperature), “he has a dry wit” (referring to the wet-dry dimension), and "he is a hot-head" (the cool-warm dimension). Imbalances among these psychological states, he believed, were one more cause for diseases. Of course, this is the first known personality typology! It had some influence on people as varied as Alfred Adler, Ivan Pavlov, and Hans Eysenck.