Physicians who were university trained during the Renaissance considered surgery beneath them. They relegated operations—which consisted mainly of bloodletting and amputations—to the barbers; although they were merely apprenticeship trained, they had the sharpest knives. Paré was among this guild of barber-surgeons. This meant that until the mid-sixteenth century, one could theoretically have a shave and an amputation at one sitting by the same practitioner. Thereafter, surgeons branched away from barbers and became separately chartered. Nonetheless, their work was demeaned.
Two holdovers from the barber-surgeon era persist. Red-and-white-striped barber poles represent the blood and bandages of the barber-surgeons; and in England, a surgeon is addressed as Mister whereas a physician is addressed as Doctor even though in recent centuries they have received the same core, university-based, medical education.
The above is from surgeon Roy A. Meals' article, A Brief History of Surgeons.