The Black Death in the fourteenth century detroyed families and human contacts, customs, and traditions. […] Bit by bit authorities combated the plague by quarantine and other measures.
The plague came from the unknown, spread everywhere, and vanished, nobody knew why. There was a common fear of this terrifying unknown.
Local barriers were erected, but they were not very efficient. State and town officials shrank from calling the disease by its name, fearing that commercial interests would suffer.
The growing power of governments made a more efficient organization possible. Extended cordons of police kept the plague outside western and central Europe.
The international health organization of the League of Nations restricts the plague to a relatively small territory in Asia. The protected region is now almost the whole world.
Fighting menaces coming from geographically unknown sources continued for centuries.