>"These places weren’t necessarily vast repositories of lost literature, but the eruption froze them nearly perfectly in time, preserving them for nearly 2,000 years—and preserving thousands of pieces of graffiti along with them."

Actually, Pompeii and Herculaneum are precisely one of the largest and most precious repositories of lost ancient literature.

http://ancphil.lsa.umich.edu/-/downloads/papyri/JankoRecentD...

http://www.newyorker.com/magazine/2015/11/16/the-invisible-l...