And at least as important are the surrounding economic, social, and archival systems for printed information. How much of the populace was literate? Was there licensing (for copyists or printers), copyright, public domain, or public libraries? Distribution systems? What sorts of material were being copied or printed? And how long did those materials physically last? My understanding is that there's a vast amount that we don't know about Ancient Rome, because their "paper" was papyrus - cheap and easy to make, but easily destroyed by rot in damp environments and by crumbling in dry environments.