Galen was not only the most eminent physicianof his time, but influenced the entire course of both physical and mental medicine through the Middle Ages and well into the modem era. Though a Greek, he was appointed physician to Marcus Aurelius, the emperor of Rome, at the age of thirty-three. He is said to have written over 500 treatises, 98 of which are still in existence. In these works he synthesized the entire history of medical thought to date, but added distinctive contributions of his own primarily in the field of anatomy and physiology.Galen did not make any extensive contributions to the diagnosis or treatment of mental disorders, but he did attempt to approach them from a scientific point of view. In general, he viewed the brain as the center of all motion and sensation, and the seat of mental disease. He recognized both physical and psychological factors in mental illness, citing as causes not only head injuries, alcoholic excess, and menstrual changes,but shock, economic reverses, and disappointment in love. He accepted Hippocrates’ theory of the four humors, and thereby recognized the dependence of temperament on variations in physiological and constitutional factors. In his own anatomical investigations, he employed bothanimal dissection and human vivisection and took an important first step toward the science of neurology. See HUMORAL THEORY.Although many of Galen’s general approaches pointed in constructive directions, the details of his medical theory and practice were a crude mixture of science, folklore and religion—and it was these details that became medical dogma for the next 1500 years. At one time he appeared to base his views on careful observation and experimentation; at another he asserted his belief in dreams and portents, primitive remedies, and supernatural intervention. He sought to relate the four humors (yellow bile, black bile, phlegm, and blood) to the four basic elements, earth, air, fire, and water, and attributed differences in disposition to states of dryness or moistness which they produced in the brain. Following Plato, Aristotle, and Hippocrates, he believed that climate was an important determinant of character, but did not make clear its relation to the humors. He appeared to take a step forward in rejecting the prevailing theory that hysteria was due to a wandering uterus, but he resorted to the humoral theory instead, claiming that this disease was produced by engorgement of the uterus with blood.Although Galen discovered experimentally that the arteries contain blood, he described the nerves as hollow tubes which carry “animal spirits” from the brain to all parts of the body. Mental disease was conceived as a disturbance in animal spirit functioning. He believed that most of the factors mentioned above, such as head injury and shock, could produce conditions of heat, humidity, coldness, etc. in the brain, which in turn brought about mania, melancholia, dementia, or imbecility. In some cases, however, he felt that the impact was more indirect, and developed a theory of “consensus” which held that the various parts of the body work together and can influence each other. An example of this view was his belief that excessive drinking does not affect the brain directly but acts through the heart or liver.Even though Galen recognized that the brain is the center for sensation and motion, he pictured these processes in purely mechanical terms, putting forth the theory that impressions are stimuli which tap on soft brain tissue like “little hammers,” while movement is initiated by striking harder areas. He also held that both the quality and quantity of brain tissue affect mental functioning, that fine tissue is involved in the process of thinking, while firm, stable tissue accounts for memory. Finally, Galen appears to have applied the same type of treatment to mental as to physical disorders. He believed that the animal spirits flowing from the brain could be influenced by administration of herbals which later became known as galenicals. He put special store by one drug in particular, theriaca, whose principal ingredient was opium. This drug was prescribed for a wide variety of physical and mental ailments, as indicated by the following statement: “It resists poison and venomous bites, cures inveterate headache, vertigo, deafness, apoplexy, epilepsy, dimness of sight, loss of voice, asthma, coughs of all kinds, spitting of blood, tightness of breath, cholic, the iliac poisons, jaundice, hardness of the spleen, stone, urinary complaints, fevers, dropsies, leprosies, the trouble to which women are subject, melancholy, and all pestilences.” Judging from this account, it would appear that the ancients had discovered a miracle drug which was equally effective for mental and physical ailments.