"For it is the doom of men that they forget." Merlin from Excalibur

...and there in that pleasant corner of the world they plied their well ordered business of living, and they heeded less and less the world outside where dark things moved, until they came to think that peace and plenty were the rule in Middle Earth and the right of all sensible folk. They forgot or ignored what little they had ever known of the Guardians and of labours of those that made possible the long peace of the Shire. They were, in fact, sheltered, but they had ceased to remember it.

from: The Fellowship of The Ring, 'Concerning Hobbits'