Fourteenth-century medical literature indicates that physicians tried many different methods to prevent and treat the plague. People understood that plague and other diseases could be transmitted person to person, and they observed that crowded cities had high death rates, especially when the weather was warm and moist. We now understand that warm, moist conditions make it easier for germs to grow and spread, but fourteenth-century people thought in terms of “poisons” in the air or “corrupted air” coming from swamps, unburied animals, or the positions of the stars. Their treatments thus focused on ridding the air and the body of these poisons and on rebalancing bodily fluids.

It is noteworthy that, in an age of mounting criticism of clerical wealth, the behavior of the clergy during the plague was often exemplary. Priests, monks, and nuns cared for the sick and buried the dead. In places like Venice, from which even physicians fled, priests remained to give what ministrations they could. Consequently, their mortality rate was phenomenally high. The German clergy, especially, suffered a severe decline in personnel in the years after 1350.

There were limits to care, however. To avoid contagion, wealthier people often fled the cities for the countryside, though sometimes this simply spread the plague faster. Some cities tried shutting their gates to prevent infected people and animals from coming in, which worked in a few cities. They also walled up houses in which there was plague, trying to isolate those who were sick from those who were still healthy.