
Augustine of Hippo
Catena Aurea · Matthäusevangelium 7
Give not that which is holy unto the dogs, neither cast ye your pearls before swine, lest they trample them under their feet, and turn again and rend you.
(Serm. in Mont. ii. 20.) Let us see now what is the holy thing, what are the dogs, what the pearls, what the swine? The holy thing is all that it were impiety to corrupt; a sin which may be committed by the will, though the thing itself be undone. The pearls are all spiritual things that are to be highly esteemed. Thus though one and the same thing may be called both the holy thing and a pearl, yet it is called holy because it is not to be corrupted; and called a pearl because it is not to be contemned.