The Greeks and the Rise of Science

Among the ancient Greeks, abnormal behaviour was still generally explained in supernatural terms; madness was a punishment sent by the gods. However, it is among the Greeks (and also the Chinese) that we begin to see the gradual evolution of a naturalistic approach to abnormal behaviour. Earliest evidence of this new approach to abnormal behaviour includes the writings attributed to the Greek physician Hippocrates. In opposition to current supernatural theories, Hippocrates set about to prove that all illness, including mental illness, was due to natural causes. He had little patience with supernatural explanations. for example, in his treatise on epilepsy, known at the time as the "sacred disease," he made the following curt observation: "If you cut open the head, you will find the brain humid, full of sweat and smelling badly. And in this way you may see that it is not a god which injured the body, but disease."
Hippocrates' achievement was threefold. First, he set himself the novel task of actually observing cases of mental disturbance and of recording his observations in as objective a manner as possible. Consequently, it is in his writings that we encounter, for the first time in Western scientific, empirical descriptions of mental disorders such  as phobia, epilepsy, and post-partum psychosis.
  Second, Hippocrates developed one of the first organic, or biological theories of abnormal behaviour. Though he recognized that external stress could have a damaging psychological effect, it was primarily internal processes that he held responsible for mental disturbance. To modern science, some appear rather crude. Hysteria for example, he attributed to a wandering uterus. (the uterus at that time was thought to be un-anchored in the female body and thus free to float about). Likewise, he believed that various personality disorders were due to an imbalance among four humours or vital fluids, in the body: phlegm, blood, black bile, and yellow bile. An excess of phlegm rendered people phlegmatic--that is, indifferent and sluggish. An excess of blood gave rise to rapid shifts in mood. Too much black bile made people melancholic, and too much yellow bile made them choleric--irritable and aggressive. How-ever primitive some of these theories may seem, they foreshadowed and in many ways made possible today's physiological and biochemical research in abnormal psychology and we still adhere to some of his theories today , in our slang.. 
Third, Hippocrates' was apparently the first Western scientist to attempt a unified classification of abnormal mental stated. H classified mental disorders into three categories: mania (abnormal excitement), melancholia (abnormal dejection), and phrenitis (brain fever).