Medical treatment in a barber shop. This early 16th century woodcut depicts the treatment of a skin disease (right) and blood letting (left) by barber surgeons. A man is being advised on use of a skin ointment and an incision is being made in a woman's arm whilst her blood is collected in a bowl. Practitioners from medieval times right through to the Renaissance believed that illness was caused by an imbalance in bodily fluids, which could be rectified by draining blood. This was often performed in barber shops, hence their red and white sign - signifying blood and the blade.