Two hundred years ago, the Reverend Sydney Smith (1771–1845) wrote what is certainly the most famous private letter he ever composed. His thoughts need almost no alteration for modern times and are still excellent advice, perhaps especially for a world in quarantine. But to savor the letter more fully, it’s worth knowing something about the man who wrote it. In February 1820, Smith was forty-eight years old and living, with his family, in rural Yorkshire, two hundred miles equidistant from the two places—London and Edinburgh—where he felt intellectually and socially at home.