Leviticus 11:44

Ye shall therefore sanctify yourselves— Here the moral reason of this separation between clean and unclean meats is given; it was to remind the Israelites of the internal purity required from them, in consequence of their separation to the service of a holy God. So the apostle: as he who hath called you is holy, so be ye holy in all manner of conversation; because it is written, Be ye holy, for I am holy: 1 Peter 1:15. So that the plain meaning of the passage is, that the Jews, being a people peculiarly devoted to God, were to be distinguished by a peculiarity of diet; which, by reminding them of their immediate relation to God, served emblematically to figure, and, as a sign, to put them in mind of their obligation to study moral purity. Agreeably whereto, Maimonides thus concludes his treatise of unclean meats: "The purity of the body leadeth one unto the purity of the soul, and the purity of the soul is a means to make us like unto God; as it is written, Ye shall sanctify yourselves, and ye shall be holy, for I am holy." Which may be thus paraphrased: "Infinitely exalted by the excellence of my nature and the greatness of my perfections, above all those pretended gods whom the pagans worship, it is but reasonable I should have votaries, distinguished in their sight by a mode of living, which may remove from all commerce or familiarity with them. This is the design of my laws: I would have them serve as a barrier to prevent my people from ever inclining to those customs which might lead them to idolatry; I would have them contribute, even in the smallest matters, to display an image of my holiness,

The soul does not contract any pollution by the touch of any animal whatsoever: but to refrain from eating or touching an animal because I forbid it, is such a proof of obedience, as will testify hearts sanctified by that love and respect which they owe to me."