[Harmless Teddy Bear]

Paper is the most important invention, then the phonetic alphabet and then the printing press.

Once the Romans lost control of Egypt and the paper industry literacy declined.

Even lacking the printing press the Romans had wide spread literacy and even mass market fiction best sellers because they had a cheap and abundant supply of paper.

The printing press was greatly aided by the fact that the concept of "rag paper" had been imported from China giving the printers once again a cheap and abundant supply of paper.

[NativeSon]

Paper is important but less important, IMO. I believe the Romans used was tablets as well.

What the Romans had was Latin and the alphabet to make known.

Many civilizations had a "written" language but not all of them could be widely learned and easily reproduced.