Story of Psychology - Morton Hunt [9]
From his theory of atoms Democritus derived an explanation of perception. Every object gives off or imprints on the atoms of the air images of itself, which travel through the air, reach the eye of the beholder, and there interact with its atoms. The product of that interaction passes to the mind and, in turn, interacts with its atoms.3 He thus anticipated, albeit in largely incorrect detail, today’s theory of vision, which holds that photons of light, emanating from an object, travel to the eye, enter it, and stimulate the endings of the optic nerves, which send messages to the brain, where they act on the brain’s neurons.
All knowledge, according to Democritus, results from the interaction of the transmitted images with the mind. Like Protagoras, he concluded that this means we have no way of knowing whether our perceptions correctly represent what is outside or whether anyone else’s perception is identical with our own. As he put it, “We know nothing for certain, but only the changes produced in our body by the forces that impinge upon it.”4 That issue would vex philosophers and psychologists from then until now, driving many of them to devise elaborate theories in the effort to escape the solipsistic trap and to affirm that there is some way to know what is really true about the world.
Hippocrates
When the early philosopher-psychologists concluded that thought occurs in the mind, it was only natural that they would also wonder why our thoughts are sometimes clear and sometimes muddled, and why most of us are mentally healthy but others are mentally ill.
Unlike their ancestors, who had believed mental dysfunction to be the work of gods or demons, they sought naturalistic answers. The most widely accepted of these was that of Hippocrates (460–377), the Father of Medicine. The son of a physician, he was born on the Greek island of Cos off the coast of what is today Turkey. He studied and practiced there, treating many of the invalids and tourists who came for the island’s hot springs and achieving such renown that far-off rulers sought him out. In 430 Athens sent for him when a plague was ravaging the city; observing that blacksmiths seemed immune to it, he ordered fires built in all public squares and, legend says, brought the disease under control. Only a handful of the seventy-odd tracts bearing his name were actually written by him, but the rest, the work of his followers, embody his ideas, which are a mixture of the sound and the absurd. For instance, he stressed diet and exercise rather than drugs, but for many diseases recommended fasting on the grounds that the more we nourish unhealthy bodies, the more we injure them.
His greatest contribution was to divorce medicine from religion and superstition. He maintained that all diseases, rather than being the work of the gods, have natural causes. In this spirit, he taught that most of the physical and mental ills of his patients had a biochemical basis (though the term “biochemical” would have meant nothing to him).
He based this explanation of health and illness on the prevailing theory of matter. Philosophers had held that the primordial stuff of the world was water, fire, air, and so on, but Empedocles concocted a more intellectually satisfying theory, which dominated Greek and later thinking. All things, he said, are made up of four “elements”—earth, air, fire, and water—held together in varying proportions by a force he called “love” or kept asunder by its opposite, “strife.”5 Though the specifics were wholly wrong, many centuries later scientists would find that his core concept—that all matter is composed of elemental substances alone or in combination—was quite right.
Hippocrates borrowed Empedocles’ four-element theory and applied it to the body. Good health, he said, is the result of a proper balance of the four bodily fluids, or “humors,” which correspond to the four elements—blood corresponding to fire, phlegm to water, black