Frankenstein is among the books I'd wish to have read years before I did

"Old literature is generally better. Period.
People were more intelligent and more expressive, it seems. The stories which, at the time, were read by ordinary people are now challenging our most capable thinkers"

I don't agree with that:
We read very little of what was made: it's precisely the best things (or rather, the more atemporal things, and the two things are not necessarily the same) which have withstood the passage of time and still find many readers to satisfy. What percentage of all the produced literature of the days of yore do we consider great?