We don’t send many letters these days, and when we do take envelopes to the post office it’s usually to pay a bill or say a formal Thank You. Centuries ago, however, letters were the only way literate people could communicate across physical distances. From the 3000-year-old courier service of the Persian Empire to the USPS today, the letter has been a poetic embodiment of humanity, representing the creation and transmission of ideas and love. One of the greatest relics of this profound history is England’s very first postage stamp—the Penny Black, which dates to May 2, 1840. On February 2, the stamp and the envelope to which it’s attached are expected to fetch anywhere from 1.5 to 2.5 million dollars at Sotheby’s. —Lucy Horowitz