Archbishop of York claims that a little blood shed during battle is just the thing the "diseased" country needs in order to heal. What the heck is he talking about? How is it possible to "heal" a country with bloodshed? Basically, York is punning on the old school medical practice of "bleeding" sick patients. The idea was that the human body was made up of four basic elements, called humors: blood, phlegm, yellow bile, and black bile. These elements were supposed to influence a person's general health, disposition, and mood. When someone got sick, one of the first things a physician did was check to make sure all the "humors" were in balance (by inspecting blood, stool, urine, mucous, and so on). If it was looking like a person had too much blood, then the solution was to drain some of it (using blood-sucking leeches or a sharp knife). Check out "Quotes" for "Weakness" if you're interested in learning more about the play's portrayal of disease.