Happy is the man that findeth wisdom, and the man that getteth understanding. For the merchandise of it is better than the merchandise of silver, and the gain thereof than fine gold. She is more precious than rubies: and all the things thou canst desire are not to be compared unto her.
But it is not only of the space in the Church which we ought to be jealous, but also of the interiors of the house of God in us, so that it might not become a house of merchandise, or a den of robbers.
Ambrose, commentary on John 2:16, Exposition of the Psalms of David 118 (PL 15 1457B)