The document discusses the Black Death plague that hit Europe in the 1300s, caused by bacteria transmitted from black rats and fleas to humans, causing symptoms like swollen and blackened lymph nodes. It killed around 25 million people in Europe between 1348-1388, decreasing the population and leading to a shortage of labor and higher wages, though it returned again in 1361. It primarily impacted children, elderly, and the poor members of society.