How do people in the middle age memorize tons of books?
They probably used memory techniques plus repetition since there wasn’t a lot to do back then haha Also, there weren’t as many books back and the rich were likely the only ones to have access to books.
is the book “memorize the faith” available for free?
In the days when books had to be hand-written, it was obviously a much more useful skill to be able to remember them - therefore, people didn’t see it as so unusual or freakish, and lots of people could do it! It’s the same kind of thing as memory competitions, I’ve always thought - scores get better gradually; as soon as people know it’s possible to memorise a pack of cards in a minute, plenty of other people can do it too, and so on.
I wrote something about pre-printing-press memorisation in my blog many years ago, and I’ve always meant to come back to the subject… http://zoomy.blogspot.co.uk/2008/07/in-which-i-postulate-mediaeval.html