2 Metaphors for rarities

The rarity of good books in every department, and the enormous quantity of imperfect, insincere books, has been the lament of all times.

Should these rarities (Faithlesse as are your wondrous promises) Lead me into the hazard of my soule And losse of such ay-lasting happinesse As all earths glories are but shaddows to? Cyprian.

2 Metaphors for  rarities