4.  And as to the tremendous question put by the facetious Encratites, why we do not eat everything?  Let this answer be given, that we turn with disgust from our excrements.  As far as dignity goes, to us flesh is grass; but as to distinction between what is and what is not serviceable, just as in vegetables, we separate the unwholesome from the wholesome, so in flesh we distinguish between that which is good and that which is bad for food.  Hemlock is a vegetable, just as vulture’s flesh is flesh; yet no one in his senses would eat henbane nor dog’s flesh unless he were in very great straits.  If he did, however, he would not sin.