Was eating a spoon of crushed emeralds an attempt to balance the humours during the Black Death?
There were a variety of beliefs at the time for the Black Death, from planetary motion, a punishment from God, to an imbalance in the four humors. There were a multitude of supposed methods for curing the Black Death, including the crushing of emeralds in a mortar and pestle and then ingesting the powder. It was believed that precious stones and metals would neutralize the plague "poison" coursing through the body. There is no direct correlation between the four humors and this method. The reality is that only the wealthy could afford such "cures," which were likely a way for the doctors of the time to increase their wages.