Origen

“ Now, having collected these things out of dissertations about stones, I say that the Saviour with a knowledge of the difference of pearls, of which some are in kind goodly and others worthless, said, “The kingdom of heaven is like unto a man that is a merchant seeking goodly pearls;” [1] for, if some of the pearls had not been worthless, it would not have been said, “to a man seeking goodly pearls.” Now among the words of all kinds which profess to announce truth, and among those who report them, he seeks pearls. ”