(From Atlas Obscura. Link to the complete article is given below.)

When books hit the road, they don’t always make their way home again. Who among us doesn’t have some rogue volumes on our shelves, pilfered from libraries or “borrowed” and then absorbed? In the 15th and 16th centuries, when book printing was in its infancy, this problem of books gone missing was especially pronounced when the volumes in question were expressly designed to roam.

In particular, texts tagged along as missionaries fanned out to proselytize across the New World. When it came to converting indigenous people to Christianity, religious texts were a powerful weapon in missionaries’ arsenals, and psalms, confessions, and other liturgical texts—written in Spanish, Latin, and scores of indigenous languages—were printed in Europe and shipped across the ocean to New Spain. This land, encompassing present-day Mexico and other portions of Central and South America, was an epicenter of conversion efforts, and it soon became a hub for the printed word, too.

It’s easy to imagine how books could become casualties of a life that was itinerant by design. “Missionaries’ whole mission was to go out and constantly be on the move, and the books were, as well,” says Melissa Moreton, an instructor at the Center for the Book at the University of Iowa. Before they did, monasteries and convents often made a bold claim to ownership. With a scalding tool, they seared distinctive marks onto the pages.

These marcas de fuego were both insurance and warning, “marking them in case someone would try to steal it from the library or convent,” says Analú López, the Ayer Indigenous Studies Librarian-in-Residence at Chicago’s Newberry library. Each order had its own symbol, which drew upon the group’s iconography. The marks made by Dominicans contain a cross, while Augustinians’ include a heart pierced by arrows, and Franciscans’ feature two crossed arms, signifying the spiritual fellowship between St. Francis and Christ. And within a given order, brands varied further from place to place.

Read more at the Atlas Obscura page here