"And she was richer in those dreams than in realities; for things seen
pass away, but the things that are unseen are eternal." That last
idea—that there's no place like the imagination (sorry, Dorothy)—could
be the series' credo."
L.M. Montgomery is not merely talking about the imagination here- she's echoing 2 Corinthians 4:18.
"While we look not at the things which are seen, but at the things which
are not seen: for the things which are seen are temporal; but the
things which are not seen are eternal."
Anne's Christian faith grows as well throughout the series.