It was Roman author and orator Cicero who said that a room without books is like a body without a soul or a book without a flask-shaped cavity in the pages. Let literature restore, or store, your spirits with today’s Groupon: for $10, you get $20 worth of used books from Better World Books. Better World Books offers free shipping to worldwide addresses and gives eco-conscious shoppers the option of purchasing offsets for the carbon footprint created from their shipment.

What began as a small-scale Indiana-based book drive has expanded sponge-capsule-like into Better World Books, an online purveyor of used and new reads that has recycled nearly 50 million books and donated more than $9 million to libraries and literacy programs around the world. Better World culls its gently worn novels, nonfiction books, and textbooks from donations, library leftovers, and campus contributions—saving each tome from the landfill while sparing trees the indignity of being reborn as Danielle Steel. A portion of every purchase goes toward building schools, starting libraries, training teachers, and providing scholarships for students in need.

Better World Books' expansive selection covers a variety of genres and subjects, from classics of the literary canon to Cannons: An Introduction to Civil War Artillery ($7.40). Wile away a dull alien abduction with Apollo's Angels: A History of Ballet ($26.98) or an engaging thriller like Stieg Larsson’s The Girl With the Dragon Tattoo ($4.98). Travel planners can grab a recent guide with all the best sights already dog-eared, and thrifty students can retain a little cash with Better World's slightly-studied textbooks, many of which are up to 90% off the list price.