Life was different in the 1300's.   There were very few large cities.   People didn't have civil rights as we know them.   There were no democracies.   Wars were fought with horses and poleaxes and maces by people who looked each other in the eye when they killed each other.   There was no electricity or refrigeration.

And there was a dangerous, terrifying animal, a creature of unspeakable horror, that stalked human beings.   In only five years, it killed 1/3 of the population of Europe.

It was ... the flea.   It lived on rats and on humans, hopping back and forth, sucking blood and spreading the bubonic plague.   It rode piggyback on the rats that stowed away on sailing vessels, and was carried all over the civilized world.

Don't assess danger by how fierce and scary something looks, or by how much noise it makes.   Watch for the tiny, hidden things.   Watch out for the fleas.