It was spring in England, and Sir Robert Cecil—Secretary of State for King James VI and I—was not happy. “I have also sent you a piece of paper folded as gentlemen use to write their letters,” he wrote to his teenage son, William, “whereas yours are like those that come out of a grammar school.” The scolding tone is timeless; William’s offense, however, is a bit dated. In the early 17th century, mass-produced envelopes had yet to be invented. Instead, letters became their own envelopes through often ingenious combinations of…
