The Humoral Theory, pondered as early as the 5th century, postulated that all people’s bodies included four “humors” resulted in health when balanced. When imbalanced, doctors believed bloodletting was a way to cure this.
Museum educator Marcy Engelman explains how doctors used tools such as the fleam, which includes multiple blades (small for children, medium for adults and large for livestock) to open the skin over a bleeding bowl, which collected the blood. Additionally, the scarificator contained 10 spring-loaded blades for a “more humane” way to take blood.
Thankfully, it seems the Humoral Theory is a thing of the past, and the modern methods for blood collection, while still not for everyone, seem a bit more manageable.