Never judge a book by its cover. Unless it's this one, anyway.

"Something that might make your skin crawl ... a book cover made of human skin. The Houghton Library's copy of Arsene Houssaye's "Des destinees de l'ame" is without a doubt bound in human skin." (Via Al Jazeera)

Yes, you read that right.

Harvard University experts said they're 99 percent sure their library's 19th century Houssaye text was indeed bound in human skin. But it wasn't the author's doing. (Via Twitter / @HarvardLibrary)

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The French writer gave the unbound text to a close friend, Dr. Ludovic Bouland, back in the 1880s, according to Houghton Library. (Via Wikimedia Commons / Etienne CarjatThe Library said Bouland later bound the book "with skin from the unclaimed body of a female mental patient who had died of a stroke." The Harvard Crimson explains Houssaye's text is a collection of essays that go all metaphysical and contemplate the human spirit. Now, why is that important?

Luckily, The Atlantic points to Dr. Bouland's manuscript note explaining the creative book cover. "This book is bound in human skin parchment on which no ornament has been stamped to preserve its elegance. By looking carefully you easily distinguish the pores of the skin. A book about the human soul deserved to have a human covering."

Believe it or not, it's not the first time human skin has been used in this way.

In 2006, a 300-year-old book bound with a slightly tanned epidermis was found in England.

And, according to the Houghton Library blog, skin-binding used to be a pretty regular practice dating back to 16th century.