The plague which swept through Europe in the 1300's was a cultural turning point in many ways. After such devastation, society had to re-build itself, and in so doing, re-designed itself. Approximately 33% of Europe died; that would be 25 million people. In some towns, everyone died; other towns had fewer casualties. Early in the century, “earthquakes, floods, tidal waves, heavy rains, and” high winds had hit Europe, leaving crops “stunted and waterlogged,” and bringing thousands to the edge of starvation; combined with poor sanitation - waste and filth were everywhere - which made a good home for the rats which carried the sickness, Europe was a ripe target for a plague. It moved quickly across the continent.
The civil response was helpful, but limited. In England, “steady leadership” sustained “order, self-control, and lawfulness.” In Florence and Venice, public health systems were established “to oversee sanitation and the burial of the dead.” But the human and spiritual response was amazing: “In the worst years of the mortality, Europeans witnessed horrors comparable to Hiroshima and Nagasaki, but even when death was everywhere and only a fool would dare to hope, the thin fabric of civilization held - sometimes by the skin of its teeth, but it held. Enough notaries, municipal and church authorities, physicians, and merchants stepped forward to keep governments and courts and churches” running. Human power alone can't generate that kind of “resiliency: even in the most extreme and horrific of circumstances, people” do actually carry on, powered by the external forces of altruism and faith.
Political and economic conditions changed after the plague: there were fewer people, more jobs, and a higher standard of living.