Ex Libris, a Latin phrase meaning “from the books,” is often employed in bookplates to indicate ownership or to collate a group of books into a collection. Bookplates are stamps or paper labels pasted inside the front or back cover of a book.
As an archivist and general bibliophile, I love opening the cover of a book and seeing a physical representation of previous book owners. It is exciting to imagine the lifespan of a bibliographic object, it’s trajectory in history from creation, through ownership, and eventually into our Rare Books collection. Bookplates are one (often beautiful) way of tracing a book’s genealogy.
The oldest known bookplates come from Germany and date back to the mid 15th Century. At this time books were costly and valuable objects, thus prone to theft. Original bookplates were utilitarian objects placed inside book covers to ward off theft from a private library.
Later bookplates often referenced this early history through humorous warnings to book borrowers.
Sir Walter Scott’s bookplate carried the monition, “Please return this book; I find that though many of my friends are poor mathematicians, they are nearly all good bookkeepers.”
Arthur T. Vance’s bookplate read:
He who lendeth a book taketh chances.
To take chances is to gamble.
It is wicked to gamble.
Kind friend, ye who seek to borrow, tempt me not to sin.
As personal libraries became more prominent, bookplates rose in international popularity taking on new forms. While bookplates originally featured a family crest or coat of arms, by the 18th C. pictorial bookplates with varied subject matter were on the rise. Bookplates became an art form unto itself and wealthy patrons began to commission bookplates by the popular artists of the day, including Aubrey Beardsley and Rockwell Kent.
Bookplates, then, are more than just signs of ownership. They become a form of personal expression for book owners and, as such, they often reveal interests, tastes, personalities of their original owner. Bookplates are a lively confluence of owner-commissioner, artist, creative medium, typography, graphic design, Zeitgeist.
While small and almost ephemeral in nature, they give valuable insight into their time of creation and their book’s provenance. 
Since the beginning of the 20th C., Amherst College Library has commissioned bookplates to commemorate gifts and funds to the Library.
You can see more examples of these bookplates in our Amherst College Library Bookplates Collection, as well as numerous personal bookplates represented in our collection of Rare Books.
I see you have included a bookplate of the late Tad Mosel, featuring masks of comedy and tragedy. Tad was my (beloved) playwriting teacher. His design choice makes sense; the text does not mention that he won a Pulitzer Prize for his stage adaptation of James Agee’s “Look Homeward Angel”. Tad also wrote many of the earliest television dramas, in the golden age of live television broadcasts. Perhaps this was not mentioned because it was deemed common knowledge to most of your readers. What a delight to come across this.