Galen

Galen (129-216 CE) was a Greek physician, author, and philosopher, working in Rome, who influenced both medical theory and practice until the middle of the 17th century CE. Owning a large, personal library, he wrote hundreds of medical treatises including anatomical, physiological, pharmaceutical, and therapeutic works. With principles based on his anatomical dissections, he spoke and wrote extensively on the anatomy of the body emphasizing the role of the heart, brain, and blood. While he criticized many of his contemporaries, he embraced the ideas put forth by the Greek physician and theorist Hippocrates (460-370 BCE), primarily his concept of the four humours that controlled the human condition: blood, phlegm, black bile, and yellow bile.