The physician shown in this painting is studying a copy of the physician, surgeon and philosopher Galen’s work, while in the background a man receives surgery on his foot. Galen’s medical theories were influential throughout the Middle Ages and into the seventeenth century. Many of Galen’s discoveries resulted from his practice of dissection. One of his most important findings was the fact that arteries carry blood, not air. Galen’s theory was founded on the widely held belief in the body being made up of four main ‘humours’. The exploration and ultimate rejection of the theory of humours during the Renaissance was an important step towards the founding of modern medicine.