Statue of Galen of Pergamon, 129-200AD, in modern Bergama, Turkey. Galen was a prominent Greek physician, surgeon and philosopher in the Roman empire. Arguably the most accomplished of all medical researchers of antiquity, Galen influenced the development of various scientific disciplines, including anatomy, physiology, pathology, pharmacology, and neurology, as well as philosophy and logic. Galen's understanding of anatomy and medicine was principally influenced by the then-current theory of humorism (also known as the four humors - Black bile, yellow bile, blood, and phlegm), as advanced by ancient Greek physicians such as Hippocrates. His theories dominated and influenced Western medical science for more than 1, 300 years. Behind Galen is the Rod of Asclepius, a serpent-entwined rod wielded by the Greek god Asclepius, a deity associated with healing and medicine.