The origins of blood-letting date back to Hippocrates in ancient Greece when the practice was recommended to both prevent as well as remedy illness. Galen also supported therapeutic bleeding because it fit with his humoral theory. According to humoral theory, illness is caused by an imbalance of the body’s four humors: blood, yellow bile, black bile, and phlegm . Thus, maintaining a balance of humors by the removal of excess blood was thought to preserve health.
The spring-lancet was predated by the thumb lancet (15th century) and fleams (17th and 18th centuries) . Both these devices required the user to...