Galen was born around 129 CE at Pergamon, in what is now western Turkey, a city famous across the Greek world for its sanctuary of Asclepius, the healing god, to which the sick traveled to sleep in a sacred precinct and receive diagnostic or therapeutic dreams. Galen himself recorded that his father, an architect, changed his intended career from philosophy to medicine after a dream instructed him to do so, and Galen credited dreams sent by Asclepius at several further points in his own medical training, treating the god's guidance as continuous with, rather than opposed to, his rigorous anatomical and clinical study.
He trained at the Pergamon Asclepeion itself and served there as physician to the city's gladiators, a post that gave him direct experience of traumatic wound anatomy no textbook study could match, before travels to Smyrna, Corinth and Alexandria completed his education. He settled in Rome around 162 CE, where his skill and confidence secured him the position of physician to a succession of emperors, Marcus Aurelius, Commodus and Septimius Severus among them, and where he produced the overwhelming bulk of the immense body of writing, on anatomy, physiology, diagnosis, pharmacology and philosophy, that made his name the single most authoritative one in medicine for the next fourteen centuries.