One of the comforts of studying history is that, no matter how bad things get, you can always find a moment in the past when things were much, much worse. Some commentators on our current crisis have been throwing around comparisons to earlier pandemics, and the Black Death of 1347 — 50 inevitably gets mentioned. Please. The Black Death wiped out half the population of Europe in the space of four years. In some places the mortality was far swifter and deadlier than that. The novelist Giovanni Boccaccio, who gave us the most vivid picture of the Black Death in literature, estimated that 100,000 people died in Florence in the four months between March and July 1348. The population of the city in 1338, according to one contemporary chronicler, stood at 120,000. Boccaccio at the time was a city tax official and saw the whole thing at ground level. Every morning bodies of the dead—husbands, wives, children, servants—were pushed out into the street where they were piled on stretchers, later on carts. They were carried …