Ambrose of Milan : You tell me that you have felt a difficulty in the text We shall sacrifice the abomination of the Egyptians to the Lord our God. But you had the means of solving it, for it is written in the book of Genesis, that a shepherd is an abomination to the Egyptians, and this not on account of the shepherd himself, but of his flocks. For the Egyptians were tillers of the ground, but Abraham and Jacob, and afterwards Moses and David, were shepherds, and in this function exercised a certain kingly discipline. The Egyptians then hated sacrifices which were duly offered; the pursuit of virtue, that is, which is perfect and replete with discipline. But that which these evil men hated is in the sight of the good sincere and pious. The licentious man hates the works of virtue, the glutton shrinks from them. And so the Egyptian's body, loving the charms of pleasure, has an aversion to the virtues of the soul, hates its rule, and shrinks from the discipline of virtue, and all such like works. But what the Egyptian shrinks from--he who is an Egyptian rather than a man--that do thou, who hast the knowledge of what befits man, embrace and follow: and shun those things which they pursue and choose; for these two things cannot agree together, wisdom and folly. Thus as wisdom and continence remove themselves from those who are, as it were, in the ranks of unwisdom and intemperance, so no foolish and incontient man has any part in what belongs to the goods and heritage of the wise and continent man. — Letter 27.1-3 Pacian of Barcelona : The Egyptians disdained the eating of sheep. But what the Egyptians abhor, the Israelites offer to God. The unjust despise a clean conscience as weak and abject, but the just turn it into a sacrifice to God of virtue. The righteous, as they worship God, offer their purity and gentleness to him. The reprobate despise these virtues and consider them foolishness. Exposition of the Old and New Testament, Exodus Paterius : The Egyptians disdained the eating of sheep. But what the Egyptians abhor, the Israelites offer to God. The unjust despise a clean conscience as weak and abject, but the just turn it into a sacrifice to God of virtue. The righteous, as they worship God, offer their purity and gentleness to him. The reprobate despise these virtues and consider them foolishness. — EXPOSITION OF THE OLD AND NEW TESTAMENT, Exodus 13