Back in 1820 the average person in England wrote only three letters a year. And with good reason. Letters in those days were mailed without a cover and could be read by anyone.

But William Mulready had an idea to ensure privacy—the envelope. On a visit to France Mulready noticed that messages from an important person often were completely enclosed in “a little paper case...impervious to the peering eyes of the curious.”

The idea of sending letters shielded from curious eyes was an instant success. The volume of letters handled by the British postal service soared beyond anyone’s expectations.

Today, there are billions of Mulready’s “little paper” envelopes safely traveling around the world.”

Bits & Pieces, May 27, 1994, pp. 1-2.