Aelius Galenus (September AD 129 – 199; Greek), better known as Galen, was a prominent Roman physician and philosopher of Greek origin, and probably the most accomplished medical researcher of the Roman period. His theories dominated and influenced Western medical science for well over a millennium. Galen developed many nerve ligation experiments that supported the theory, which is still believed today, that the brain controls all the motions of the muscles by means of the cranial and peripheral nervous systems. Galen wrote a small work #### called "That the Best Physician is also a Philosopher", and he saw himself as being both, which meant grounding medical practice in theoretically sound knowledge or "philosophy" as it was called in his time. Galen was very interested in the dispute between Rationalist and Empiricist medical sects, and his use of direct observation, dissection and vivisection in medical training and as a way to ground medical practice can be understood as considering both of those perspectives and constructing a more complex and nuanced middle ground that avoided problems with each position. Galen's fame rested on his anatomical demonstrations, success with influential patrons where others had failed, his learning and his rhetoric. His background and wealth. Galen developed an interest in anatomy from his studies of Herophilus and Erasistratus, who had dissected the human body and even living bodies (vivisection). Although Galen studied the human body, dissection of human corpses was against Roman law, so instead he performed vivisections on pigs, apes, and other animals to study the function of the kidneys and the spinal cord. Galen performed many audacious operations including brain and eye surgeries that w ere not tried again for almost two millennia.
Works:
Galen's works covered a wide range of topics, from anatomy, physiology, and medicine to logic and philosophy, both summarising what was known and adding his own observations. His writings pay homage to, amongst others, Plato, Aristotle ,but above all to Hippocrates, whom he refers to as "divine" Thus much of his explanation of pathology relies on Hippocrates' humoral theories. Galen produced more work than any author in antiquity, and may have possibly written up to 600 treatises, although less than a third of his works have survived. a fire in the Temple of Peace destroyed many of his works, particularly treatises on philosophy. Because Galen's works were not translated into Latin in the ancient period, and because of the collapse of the Roman Empire in the West, the study of Galen, along with the Greek medical tradition as a whole, went into decline in Western Europe during the Early Middle Ages, when very few Latin scholars could read Greek. In the Abbasid period (after 750 AD) Arab Muslims began to be interested in Greek scientific and medical texts for the first time, the first major translator of Galen into Arabic was the Syrian Christian Hunayn ibn Isaac. Hunayn translated (c.830-870) 129 works of Galen into Arabic. Galen's insistence on a rational systematic approach to medicine set the template for Islamic medicine, which rapidly spread throughout the Arab Empire. various attempts have been made to classify Galen's vast output. For instance Coxe (1846) lists a Prolegomena, or introductory books, followed by 7 classes of treatise embracing Physiology (28 vols.), Hygiene (12), Aetiology (19), Semeiotics (14), Pharmacy (10), Blood letting (4) and Therapeutics (17), in addition to 4 of aphorisms, and spurious works.