Pseudo-Chrysostom
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.
Otherwise; The dog and the swine are unclean animals; the dog indeed in every respect, as he neither chews the cud, nor divides the hoof; but swine in one respect only, seeing they divide the hoof, though they do not chew the cud. Hence I think that we are to understand by the dog, the Gentiles who are altogether unclean, both in their life, and in their faith; but by the swine are to be understood heretics, because they seem to call upon the name of the Lord. Give not therefore that which is holy to the dogs, for that baptism and the other sacraments are not to be given but to them that have the faith. In like manner the mysteries of the truth, that is, the pearls, are not to be given but to such as desire the truth and live with human reason. If then you cast them to the swine, that is, to such as are grovelling in impurity of life, they do not understand their preciousness, but value them like to other worldly fables, and tread them under foot with their carnal life.