Part Five 5:

That began to change in the Middle Ages. It’s believed to be around that time, as notions of courtly love gained influence in Europe, that some celebrants found a more cheerful way of explaining why Saint Valentine’s feast day should be a time to think about romance. Poets, most famously Geoffrey Chaucer in his 14th-century “Parliament of Fowls,” were the ones who put it together that the day fell right around the time of year when birds would sing their mating songs to get ready for the spring. He wrote, per one translation, “For this was on Saint Valentine’s day / When every bird cometh there to chose his mate.” A February 1477 letter in which Margery Brews of Norfolk, England, called her fiancé John Paston “my right well-beloved valentine” is considered the oldest known Valentine written in English (and is now housed at the British Library).

Such romantic phrases and images started appearing on greeting cards once the industrial revolution in the mid-19th century enabled the production of mass quantities of affordable consumer goods. Cadbury’s heart-shaped boxes of chocolates appeared in the 1860s, Hershey’s Kisses in 1907, and Hallmark Valentine’s Day cards in 1913 — all of which have remained Valentine’s Day traditions.