incunabulum
A book, single sheet, or image that was printed before the year 1501 in Europe.
Sebastian, a profound student of such lore, had long believed that the book was a mere medieval legend; and he had been startled as well as gratified when he found this copy on the shelves of a dealer in old manuscripts and incunabula.
The cradle, birthplace, or origin of something.
Where it comes from
Borrowed from Latin incūnābulum (“cradle, origin”).
Adapted from the Wiktionary entry incunabulum (CC BY-SA 4.0).