The Black Book of Carmarthen, the oldest surviving medieval manuscript written in Welsh, has proven to be even more interesting than anyone even knew. Two scholars from the University of Cambridge – doctoral student Myriah Williams and Paul Russell, a professor in the department of Anglo-Saxon, Celtic and Norse languages – examined its pages under UV light and found fascinating marginalia not visible to the naked eye. Coming into view for the first time are ghostly faces along with reflective text that were added during the 13-15th centuries.

The book, which contains various types of poetry including religious verse, is thought to be the work of a single scribe – despite the fact that the size and style of the script varies throughout the 54-page book. Among the poems are two attributed to the legendary Merlin. And the first poem is said to be a conversation between Merlin and Taliesin, the renowned 6th Century Welsh.

In a statement, Ms. Williams noted that, "The margins of manuscripts often contain medieval and early modern reactions to the text, and these can cast light on what our ancestors thought about what they were reading,"

Over the course of its history, the ‘Black Book’ fell into various hands and the researchers speculate that an owner in the 16th century, Jaspar Gryffyth, was likely the one responsible for erasing the centuries of doodles and ruminations that show up under UV lighting. His name is written in Hebrew in the book.

The book is relatively small – measuring 6.7” x 5” and the pages are made of vellum (animal skin). The Black Book was purchased in 1904 by Sir John Williams, founder of the National Library of Wales.