Off Topic: The weird history of handwriting

In his Confessions, written around the year 400 AD, Saint Augustine mentions his shock upon coming across a friend who was reading a book without saying the words out loud as he went. Reading in your head! It's odd in 2021 to read about Augustine's astonishment and realise that the act of silently reading to yourself was an act that had to be learned. It arrived a surprisingly long time after written language.