From the website:
Rudy traces the postcard's origins to 1490, when a nun inscribed the back of a single-leaf, miniature painting of St. Barbara and sent it to another nun. The recipient then placed the folio, "scrap-book style," into a manuscript prayer book, where she cobbled together a selection of other images, presumably gifts from other nuns. Laurinda Dixon, professor of art and music histories at SU, says that these beautiful, personalized paintings were, in effect, the first postcards, with an image on one side and a greeting on the other. "Dr. Rudy links this medieval practice to modern postcards, which we send to friends and family members and save as mementos," she adds.
The lecture is free and open to the public. For more information, visit the Medievalists.net website.