What does ayn rand mean in anthem,"they were not soft and rolled, they had hard shells of cloth and leather;"?

-Ayn Rand's Anthem 100 centennial edition Page 91 2nd paragraph 4th-5th line down or 3rd sentenceAnthem takes place in a dark ages medieval-type setting. It's not a futuristic dystopa filled with traditional rundown technical gadgetry. The "soft/rolled" thingies the narrator pictures are scrolls, and the things with "hard shells of cloth and leather" are hard-cover books. In Rand's envisioned future, litereature has taken a step back and writing is again done in papyrus scrolls rather than the comparatively more economical and practical modern-day book format.