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