On one hand, I am tempted to quote Plato(?) on how books ruin people's ability to remember things. On the other hand, if you don't regularly exercise your facilities, physical or mental, they do deteriorate, no question about it.
Yep, in Plato's Phaedrus. https://www.historyofinformation.com/detail.php?id=3439
Plato wrote the story, attributing it to Socrates. The story is about the egyptian inventor Theuth who showed his inventions of numbers, leters, etc. to the god Thamus (Ammon). The god liked the numbers, but for writing said:
> "For this invention will produce forgetfulness in the minds of those who learn to use it, because they will not practice their memory. Their trust in writing, produced by external characters which are no part of themselves, will discourage the use of their own memory within them. You have invented an elixir not of memory, but of reminding; and you offer your pupils the appearance of wisdom, not true wisdom, for they will read many things without instruction and will therefore seem [275b] to know many things, when they are for the most part ignorant and hard to get along with, since they are not wise, but only appear wise."
EDIT: It's a little more complex than that. I think Plato identifies the "soul" as where the forms maintain their persistence. So in a sense everybody possess reality within them. Memory is a portal into the soul; it's how you "see" it. Notably, the Christian (and especially Augustinian Catholic) concept of conscience is derived from this Platonic model. That's why Christians say that knowledge of right and wrong--as well as God, etc--is imbued within every person from conception. I doubt that that's a particularly novel idea among world religions, but the way it plays out in Christian theology is heavily derivative of Plato's model.