“Time will bring to light whatever is hidden”*…
A fore-edge painting is an image on the edges of the pages of a book. The work can only be seen when the pages are fanned (as illustrated in the GIF above and the videos below). When the book is closed, the image is obscured by the gilding– the gold leaf applied to the edges of the page.
Fore-edge paintings first arose during the European Middle Ages but came to prominence during the mid-17th century to the late 19th century. Anne C. Bromer for the Boston Public Library [which holds one of the finest collections of fore-edge paintings in the U.S.] writes, “Most fore-edge painters working for binding firms did not sign their work, which explains why it is difficult to pinpoint and date the hidden paintings.”
As we hunt for Easter eggs, we might spare an ecumenical thought for Ramon Llull; he died on this date in 1315 [source]. A philosopher, logician, poet, and theologian who was heavily influenced by Islam, he is credited with the first major work of Catalan literature (the romantic novel Blanquerna), with having anticipated by several centuries prominent work on elections theory, and with pioneering work on computation theory (largely given his influence on Leibniz).
One of the earliest Encyclopedists, he gave up the life of a courtier (to King James of Aragon) first to become a hermit, then a Franciscan. After a 1297 meeting with Duns Scotus, he was given the nickname Doctor Illuminatus.