Deuteronomy 14

Deuteronomy 14:3

Clement of Alexandria: Among the Jews, frugality was made a matter of precept by a very wise dispensation of the law. The Educator forbade them the use of innumerable things. He explained the reasons, the spiritual ones hidden, the material ones obvious, but all of which they trusted. Some animals [were forbidden] because they were [not] cloven-footed; others, because they did not ruminate their food; a third class, because they, alone among all the fish of the seas, had no scales; until finally there were only a few things left fit for food. And even of those he permitted them to touch, he placed a prohibition on the ones found dead or offered to idols or strangled. They could not even touch them. He imposed upon them a contrary course of action until the inclination engendered by habits of easy living be broken, because it is difficult for one who indulges in pleasures to keep himself from returning to them. — The Instructor Book 2

Richard Challoner: Unclean: See the annotations on Lev. 11.

Deuteronomy 14:4

Ambrose of Milan: And therefore, according to the Law, clean animals have horns: for the Law is spiritual. For those who are able to repel the allurements of this world with the word of God and the observance of virtue, they seem to be fortified with horns like the helmets of their own heads. And rightly, the power of an astonishing speech is said to be like a horn, which ignites the good soldiers of Christ to battle so that we may snatch the spoils from the enemy, the devil. Therefore, we are on the battlefield, and we see many of us held captive in the enemy’s camp: they must be freed from the heavy yoke of slavery. — On the Blessings of the Patriarchs