In the later Middle Ages, with the rise of universities and cathedral schools in urban areas across Europe, regulated organizations began to professionalize the trade of the surgeon or barber-surgeon (Siraisi 18). In Venice, there was a College of Physicians by 1316 which focused on a wide range of different medical practices (Siraisi 18). Bloodletting, however, was by far the most common medical practice throughout the Middle Ages, especially as it was less painful than cautery, and since all humors were believed to be in the blood, and since it was believed that by “disordered complexion” these humors could transform into unwanted secondary humors, bloodletting, or phlebotomy, allowed these unwanted humors to be removed from the body before the liver could produce more clean, pure blood (Siraisi 139).