Summa Th. I-II EN Qu.102 a.6

Whether there was any reasonable cause for the ceremonial observances?

Objection: 1. It would seem that there was no reasonable cause for the ceremonial observances. Because, as the Apostle says (1Tm 4,4), "every creature of God is good, and nothing to be rejected that is received with thanksgiving." It was therefore unfitting that they should be forbidden to eat certain foods, as being unclean according to Lv 11 [*Cf. Dt 14].
2. Further, just as animals are given to man for food, so also are herbs: wherefore it is written (Gn 9,3): "As the green herbs have I delivered all" flesh "to you." But the Law did not distinguish any herbs from the rest as being unclean, although some are most harmful, for instance, those that are poisonous. Therefore it seems that neither should any animals have been prohibited as being unclean.
3. Further, if the matter from which a thing is generated be unclean, it seems that likewise the thing generated therefrom is unclean. But flesh is generated from blood. Since therefore all flesh was not prohibited as unclean, it seems that in like manner neither should blood have been forbidden as unclean; nor the fat which is engendered from blood.
4. Further, Our Lord said (Mt 10,28 Lc 12,4), that those should not be feared "that kill the body," since after death they "have no more that they can do": which would not be true if after death harm might come to man through anything done with his body. Much less therefore does it matter to an animal already dead how its flesh be cooked. Consequently there seems to be no reason in what is said, Ex 23,19: "Thou shalt not boil a kid in the milk of its dam."
5. Further, all that is first brought forth of man and beast, as being most perfect, is commanded to be offered to the Lord (Ex 13). Therefore it is an unfitting command that is set forth in Lv 19,23: "when you shall be come into the land, and shall have planted in it fruit trees, you shall take away the uncircumcision [*'Praeputia,' which Douay version renders 'first fruits'] of them," i.e. the first crops, and they "shall be unclean to you, neither shall you eat of them."
6. Further, clothing is something extraneous to man's body. Therefore certain kinds of garments should not have been forbidden to the Jews: for instance (Lv 19,19): "Thou shalt not wear a garment that is woven of two sorts": and (Dt 22,5): "A woman shall not be clothed with man's apparel, neither shall a man use woman's apparel": and further on (Dt 22,11): "Thou shalt not wear a garment that is woven of woolen and linen together."
7. Further, to be mindful of God's commandments concerns not the body but the heart. Therefore it is unsuitably prescribed (Dt 6,8, seqq.) that they should "bind" the commandments of God "as a sign" on their hands; and that they should "write them in the entry"; and (Nb 15,38, seqq.) that they should "make to themselves fringes in the corners of their garments, putting in them ribands of blue . . . they may remember . . . the commandments of the Lord."
8. Further, the Apostle says (1Co 9,9) that God does not "take care for oxen," and, therefore, neither of other irrational animals. Therefore without reason is it commanded (Dt 22,6): "If thou find, as thou walkest by the way, a bird's nest in a tree . . . thou shalt not take the dam with her young"; and (Dt 25,4): "Thou shalt not muzzle the ox that treadeth out thy corn"; and (Lv 19,19): "Thou shalt not make thy cattle to gender with beasts of any other kind."
9. Further, no distinction was made between clean and unclean plants. Much less therefore should any distinction have been made about the cultivation of plants. Therefore it was unfittingly prescribed (Lv 19,19): "Thou shalt not sow thy field with different seeds"; and (Dt 22,9, seqq.): "Thou shalt sow thy vineyard with divers seeds"; and: "Thou shalt not plough with an ox and an ass together."
0. Further, it is apparent that inanimate things are most of all subject to the power of man. Therefore it was unfitting to debar man from taking silver and gold of which idols were made, or anything they found in the houses of idols, as expressed in the commandment of the Law (Dt 7,25, seqq.). It also seems an absurd commandment set forth in Dt 23,13, that they should "dig round about and . . . cover with earth that which they were eased of."
1. Further, piety is required especially in priests. But it seems to be an act of piety to assist at the burial of one's friends: wherefore Tobias is commended for so doing (Tb 1,20, seqq.). In like manner it is sometimes an act of piety to marry a loose woman, because she is thereby delivered from sin and infamy. Therefore it seems inconsistent for these things to be forbidden to priests (Lv 21).

On the contrary It is written (Dt 18,14): "But thou art otherwise instructed by the Lord thy God": from which words we may gather that these observances were instituted by God to be a special prerogative of that people. Therefore they are not without reason or cause.
I answer that The Jewish people, as stated above (Article [5]), were specially chosen for the worship of God, and among them the priests themselves were specially set apart for that purpose. And just as other things that are applied to the divine worship, need to be marked in some particular way so that they be worthy of the worship of God; so too in that people's, and especially the priests', mode of life, there needed to be certain special things befitting the divine worship, whether spiritual or corporal. Now the worship prescribed by the Law foreshadowed the mystery of Christ: so that whatever they did was a figure of things pertaining to Christ, according to 1Co 10,11: "All these things happened to them in figures." Consequently the reasons for these observances may be taken in two ways, first according to their fittingness to the worship of God; secondly, according as they foreshadow something touching the Christian mode of life.

Reply to Objection: 1. As stated above (Article [5], ad 4,5), the Law distinguished a twofold pollution or uncleanness; one, that of sin, whereby the soul was defiled; and another consisting in some kind of corruption, whereby the body was in some way infected. Speaking then of the first-mentioned uncleanness, no kind of food is unclean, or can defile a man, by reason of its nature; wherefore we read (Mt 15,11): "Not that which goeth into the mouth defileth a man; but what cometh out of the mouth, this defileth a man": which words are explained (Mt 15,17) as referring to sins. Yet certain foods can defile the soul accidentally; in so far as man partakes of them against obedience or a vow, or from excessive concupiscence; or through their being an incentive to lust, for which reason some refrain from wine and flesh-meat.If, however, we speak of bodily uncleanness, consisting in some kind of corruption, the flesh of certain animals is unclean, either because like the pig they feed on unclean things; or because their life is among unclean surroundings: thus certain animals, like moles and mice and such like, live underground, whence they contract a certain unpleasant smell; or because their flesh, through being too moist or too dry, engenders corrupt humors in the human body. Hence they were forbidden to eat the flesh of flat-footed animals, i.e. animals having an uncloven hoof, on account of their earthiness; and in like manner they were forbidden to eat the flesh of animals that have many clefts in their feet, because such are very fierce and their flesh is very dry, such as the flesh of lions and the like. For the same reason they were forbidden to eat certain birds of prey the flesh of which is very dry, and certain water-fowl on account of their exceeding humidity. In like manner certain fish lacking fins and scales were prohibited on account of their excessive moisture; such as eels and the like. They were, however, allowed to eat ruminants and animals with a divided hoof, because in such animals the humors are well absorbed, and their nature well balanced: for neither are they too moist, as is indicated by the hoof; nor are they too earthly, which is shown by their having not a flat but a cloven hoof. Of fishes they were allowed to partake of the drier kinds, of which the fins and scales are an indication, because thereby the moist nature of the fish is tempered. Of birds they were allowed to eat the tamer kinds, such as hens, partridges, and the like. Another reason was detestation of idolatry: because the Gentiles, and especially the Egyptians, among whom they had grown up, offered up these forbidden animals to their idols, or employed them for the purpose of sorcery: whereas they did not eat those animals which the Jews were allowed to eat, but worshipped them as gods, or abstained, for some other motive, from eating them, as stated above (Article [3], ad 2). The third reason was to prevent excessive care about food: wherefore they were allowed to eat those animals which could be procured easily and promptly.With regard to blood and fat, they were forbidden to partake of those of any animals whatever without exception. Blood was forbidden, both in order to avoid cruelty, that they might abhor the shedding of human blood, as stated above (Article [3], ad 8); and in order to shun idolatrous rite whereby it was customary for men to collect the blood and to gather together around it for a banquet in honor of the idols, to whom they held the blood to be most acceptable. Hence the Lord commanded the blood to be poured out and to be covered with earth (Lv 17,13). For the same reason they were forbidden to eat animals that had been suffocated or strangled: because the blood of these animals would not be separated from the body: or because this form of death is very painful to the victim; and the Lord wished to withdraw them from cruelty even in regard to irrational animals, so as to be less inclined to be cruel to other men, through being used to be kind to beasts. They were forbidden to eat the fat: both because idolaters ate it in honor of their gods; and because it used to be burnt in honor of God; and, again, because blood and fat are not nutritious, which is the cause assigned by Rabbi Moses (Doct. Perplex. iii). The reason why they were forbidden to eat the sinews is given in Gn 32,32, where it is stated that "the children of Israel . . . eat not the sinew . . . because he touched the sinew of" Jacob's "thing and it shrank."The figurative reason for these things is that all these animals signified certain sins, in token of which those animals were prohibited. Hence Augustine says (Contra Faustum iv, 7): "If the swine and lamb be called in question, both are clean by nature, because all God's creatures are good: yet the lamb is clean, and the pig is unclean in a certain signification. Thus if you speak of a foolish, and of a wise man, each of these expressions is clean considered in the nature of the sound, letters and syllables of which it is composed: but in signification, the one is clean, the other unclean." The animal that chews the cud and has a divided hoof, is clean in signification. Because division of the hoof is a figure of the two Testaments: or of the Father and Son: or of the two natures in Christ: of the distinction of good and evil. While chewing the cud signifies meditation on the Scriptures and a sound understanding thereof; and whoever lacks either of these is spiritually unclean. In like manner those fish that have scales and fins are clean in signification. Because fins signify the heavenly or contemplative life; while scales signify a life of trials, each of which is required for spiritual cleanness. Of birds certain kinds were forbidden. In the eagle which flies at a great height, pride is forbidden: in the griffon which is hostile to horses and men, cruelty of powerful men is prohibited. The osprey, which feeds on very small birds, signifies those who oppress the poor. The kite, which is full of cunning, denotes those who are fraudulent in their dealings. The vulture, which follows an army, expecting to feed on the carcases of the slain, signifies those who like others to die or to fight among themselves that they may gain thereby. Birds of the raven kind signify those who are blackened by their lusts; or those who lack kindly feelings, for the raven did not return when once it had been let loose from the ark. The ostrich which, though a bird, cannot fly, and is always on the ground, signifies those who fight God's cause, and at the same time are taken up with worldly business. The owl, which sees clearly at night, but cannot see in the daytime, denotes those who are clever in temporal affairs, but dull in spiritual matters. The gull, which flies both in the air and swims in the water, signifies those who are partial both to Circumcision and to Baptism: or else it denotes those who would fly by contemplation, yet dwell in the waters of sensual delights. The hawk, which helps men to seize the prey, is a figure of those who assist the strong to prey on the poor. The screech-owl, which seeks its food by night but hides by day, signifies the lustful man who seeks to lie hidden in his deeds of darkness. The cormorant, so constituted that it can stay a long time under water, denotes the glutton who plunges into the waters of pleasure. The ibis is an African bird with a long beak, and feeds on snakes; and perhaps it is the same as the stork: it signifies the envious man, who refreshes himself with the ills of others, as with snakes. The swan is bright in color, and by the aid of its long neck extracts its food from deep places on land or water: it may denote those who seek earthly profit though an external brightness of virtue. The bittern is a bird of the East: it has a long beak, and its jaws are furnished with follicules, wherein it stores its food at first, after a time proceeding to digest it: it is a figure of the miser, who is excessively careful in hoarding up the necessaries of life. The coot [*Douay: 'porphyrion.' St. Thomas' description tallies with the coot or moorhen: though of course he is mistaken about the feet differing from one another.] has this peculiarity apart from other birds, that it has a webbed foot for swimming, and a cloven foot for walking: for it swims like a duck in the water, and walks like a partridge on land: it drinks only when it bites, since it dips all its food in water: it is a figure of a man who will not take advice, and does nothing but what is soaked in the water of his own will. The heron [*Vulg.: 'herodionem'], commonly called a falcon, signifies those whose "feet are swift to shed blood" (Ps 13,3). The plover [*Here, again, the Douay translators transcribed from the Vulgate: 'charadrion'; 'charadrius' is the generic name for all plovers.], which is a garrulous bird, signifies the gossip. The hoopoe, which builds its nest on dung, feeds on foetid ordure, and whose song is like a groan, denotes worldly grief which works death in those who are unclean. The bat, which flies near the ground, signifies those who being gifted with worldly knowledge, seek none but earthly things. Of fowls and quadrupeds those alone were permitted which have the hind-legs longer than the forelegs, so that they can leap: whereas those were forbidden which cling rather to the earth: because those who abuse the doctrine of the four Evangelists, so that they are not lifted up thereby, are reputed unclean. By the prohibition of blood, fat and nerves, we are to understand the forbidding of cruelty, lust, and bravery in committing sin.
2. Men were wont to eat plants and other products of the soil even before the deluge: but the eating of flesh seems to have been introduced after the deluge; for it is written (Gn 9,3): "Even as the green herbs have I delivered . . . all" flesh "to you." The reason for this was that the eating of the products of the soil savors rather of a simple life; whereas the eating of flesh savors of delicate and over-careful living. For the soil gives birth to the herb of its own accord; and such like products of the earth may be had in great quantities with very little effort: whereas no small trouble is necessary either to rear or to catch an animal. Consequently God being wishful to bring His people back to a more simple way of living, forbade them to eat many kinds of animals, but not those things that are produced by the soil. Another reason may be that animals were offered to idols, while the products of the soil were not.
3. The Reply to the Third Objection is clear from what has been said (ad 1).
4. Although the kid that is slain has no perception of the manner in which its flesh is cooked, yet it would seem to savor of heartlessness if the dam's milk, which was intended for the nourishment of her offspring, were served up on the same dish. It might also be said that the Gentiles in celebrating the feasts of their idols prepared the flesh of kids in this manner, for the purpose of sacrifice or banquet: hence (Ex 23) after the solemnities to be celebrated under the Law had been foretold, it is added: "Thou shalt not boil a kid in the milk of its dam." The figurative reason for this prohibition is this: the kid, signifying Christ, on account of "the likeness of sinful flesh" (Rm 8,3), was not to be seethed, i.e. slain, by the Jews, "in the milk of its dam," i.e. during His infancy. Or else it signifies that the kid, i.e. the sinner, should not be boiled in the milk of its dam, i.e. should not be cajoled by flattery.
5. The Gentiles offered their gods the first-fruits, which they held to bring them good luck: or they burnt them for the purpose of secrecy. Consequently (the Israelites) were commanded to look upon the fruits of the first three years as unclean: for in that country nearly all the trees bear fruit in three years' time; those trees, to wit, that are cultivated either from seed, or from a graft, or from a cutting: but it seldom happens that the fruit-stones or seeds encased in a pod are sown: since it would take a longer time for these to bear fruit: and the Law considered what happened most frequently. The fruits, however, of the fourth year, as being the firstlings of clean fruits, were offered to God: and from the fifth year onward they were eaten.The figurative reason was that this foreshadowed the fact that after the three states of the Law (the first lasting from Abraham to David, the second, until they were carried away to Babylon, the third until the time of Christ), the Fruit of the Law, i.e. Christ, was to be offered to God. Or again, that we must mistrust our first efforts, on account of their imperfection.
6. It is said of a man in Si 19,27, that "the attire of the body . . . " shows "what he is." Hence the Lord wished His people to be distinguished from other nations, not only by the sign of the circumcision, which was in the flesh, but also by a certain difference of attire. Wherefore they were forbidden to wear garments woven of woolen and linen together, and for a woman to be clothed with man's apparel, or vice versa, for two reasons. First, to avoid idolatrous worship. Because the Gentiles, in their religious rites, used garments of this sort, made of various materials. Moreover in the worship of Mars, women put on men's armor; while, conversely, in the worship of Venus men donned women's attire. The second reason was to preserve them from lust: because the employment of various materials in the making of garments signified inordinate union of sexes, while the use of male attire by a woman, or vice versa, has an incentive to evil desires, and offers an occasion of lust. The figurative reason is that the prohibition of wearing a garment woven of woolen and linen signified that it was forbidden to unite the simplicity of innocence, denoted by wool, with the duplicity of malice, betokened by linen. It also signifies that woman is forbidden to presume to teach, or perform other duties of men: or that man should not adopt the effeminate manners of a woman.
7. As Jerome says on Mt 23,6, "the Lord commanded them to make violet-colored fringes in the four corners of their garments, so that the Israelites might be distinguished from other nations." Hence, in this way, they professed to be Jews: and consequently the very sight of this sign reminded them of their law.When we read: "Thou shalt bind them on thy hand, and they shall be ever before thy eyes [Vulg.: 'they shall be and shall move between thy eyes'], the Pharisees gave a false interpretation to these words, and wrote the decalogue of Moses on a parchment, and tied it on their foreheads like a wreath, so that it moved in front of their eyes": whereas the intention of the Lord in giving this commandment was that they should be bound in their hands, i.e. in their works; and that they should be before their eyes, i.e. in their thoughts. The violet-colored fillets which were inserted in their cloaks signify the godly intention which should accompany our every deed. It may, however, be said that, because they were a carnal-minded and stiff-necked people, it was necessary for them to be stirred by these sensible things to the observance of the Law.
8. Affection in man is twofold: it may be an affection of reason, or it may be an affection of passion. If a man's affection be one of reason, it matters not how man behaves to animals, because God has subjected all things to man's power, according to Ps 8,8: "Thou hast subjected all things under his feet": and it is in this sense that the Apostle says that "God has no care for oxen"; because God does not ask of man what he does with oxen or other animals.But if man's affection be one of passion, then it is moved also in regard to other animals: for since the passion of pity is caused by the afflictions of others; and since it happens that even irrational animals are sensible to pain, it is possible for the affection of pity to arise in a man with regard to the sufferings of animals. Now it is evident that if a man practice a pitiful affection for animals, he is all the more disposed to take pity on his fellow-men: wherefore it is written (Pr 11,10): "The just regardeth the lives of his beasts: but the bowels of the wicked are cruel." Consequently the Lord, in order to inculcate pity to the Jewish people, who were prone to cruelty, wished them to practice pity even with regard to dumb animals, and forbade them to do certain things savoring of cruelty to animals. Hence He prohibited them to "boil a kid in the milk of its dam"; and to "muzzle the ox that treadeth out the corn"; and to slay "the dam with her young." It may, nevertheless, be also said that these prohibitions were made in hatred of idolatry. For the Egyptians held it to be wicked to allow the ox to eat of the grain while threshing the corn. Moreover certain sorcerers were wont to ensnare the mother bird with her young during incubation, and to employ them for the purpose of securing fruitfulness and good luck in bringing up children: also because it was held to be a good omen to find the mother sitting on her young.As to the mingling of animals of divers species, the literal reason may have been threefold. The first was to show detestation for the idolatry of the Egyptians, who employed various mixtures in worshipping the planets, which produce various effects, and on various kinds of things according to their various conjunctions. The second reason was in condemnation of unnatural sins. The third reason was the entire removal of all occasions of concupiscence. Because animals of different species do not easily breed, unless this be brought about by man; and movements of lust are aroused by seeing such things. Wherefore in the Jewish traditions we find it prescribed as stated by Rabbi Moses that men shall turn away their eyes from such sights.The figurative reason for these things is that the necessities of life should not be withdrawn from the ox that treadeth the corn, i.e. from the preacher bearing the sheaves of doctrine, as the Apostle states (1Co 9,4, seqq.). Again, we should not take the dam with her young: because in certain things we have to keep the spiritual senses, i.e. the offspring, and set aside the observance of the letter, i.e. the mother, for instance, in all the ceremonies of the Law. It is also forbidden that beast of burden, i.e. any of the common people, should be allowed to engender, i.e. to have any connection, with animals of another kind, i.e. with Gentiles or Jews.
9. All these minglings were forbidden in agriculture; literally, in detestation of idolatry. For the Egyptians in worshipping the stars employed various combinations of seeds, animals and garments, in order to represent the various connections of the stars. Or else all these minglings were forbidden in detestation of the unnatural vice.They have, however, a figurative reason. For the prohibition: "Thou shalt not sow thy field with different seeds," is to be understood, in the spiritual sense, of the prohibition to sow strange doctrine in the Church, which is a spiritual vineyard. Likewise "the field," i.e. the Church, must not be sown "with different seeds," i.e. with Catholic and heretical doctrines. Neither is it allowed to plough "with an ox and an ass together"; thus a fool should not accompany a wise man in preaching, for one would hinder the other.
0. [*The Reply to the Tenth Objection is lacking in the codices. The solution given here is found in some editions, and was supplied by Nicolai.] Silver and gold were reasonably forbidden (Dt 7) not as though they were not subject to the power of man, but because, like the idols themselves, all materials out of which idols were made, were anathematized as hateful in God's sight. This is clear from the same chapter, where we read further on (Dt 7,26): "Neither shalt thou bring anything of the idol into thy house, lest thou become an anathema like it." Another reason was lest, by taking silver and gold, they should be led by avarice into idolatry to which the Jews were inclined. The other precept (Dt 23) about covering up excretions, was just and becoming, both for the sake of bodily cleanliness; and in order to keep the air wholesome; and by reason of the respect due to the tabernacle of the covenant which stood in the midst of the camp, wherein the Lord was said to dwell; as is clearly set forth in the same passage, where after expressing the command, the reason thereof is at once added, to wit: "For the Lord thy God walketh in the midst of thy camp, to deliver thee, and to give up thy enemies to thee, and let thy camp be holy [i.e. clean], and let no uncleanness appear therein." The figurative reason for this precept, according to Gregory (Moral. xxxi), is that sins which are the fetid excretions of the mind should be covered over by repentance, that we may become acceptable to God, according to Ps 31,1: "Blessed are they whose iniquities are forgiven, and whose sins are covered." Or else according to a gloss, that we should recognize the unhappy condition of human nature, and humbly cover and purify the stains of a puffed-up and proud spirit in the deep furrow of self-examination.
1. Sorcerers and idolatrous priests made use, in their rites, of the bones and flesh of dead men. Wherefore, in order to extirpate the customs of idolatrous worship, the Lord commanded that the priests of inferior degree, who at fixed times served in the temple, should not "incur an uncleanness at the death" of anyone except of those who were closely related to them, viz. their father or mother, and others thus near of kin to them. But the high-priest had always to be ready for the service of the sanctuary; wherefore he was absolutely forbidden to approach the dead, however nearly related to him. They were also forbidden to marry a "harlot" or "one that has been put away," or any other than a virgin: both on account of the reverence due to the priesthood, the honor of which would seem to be tarnished by such a marriage: and for the sake of the children who would be disgraced by the mother's shame: which was most of all to be avoided when the priestly dignity was passed on from father to son. Again, they were commanded to shave neither head nor beard, and not to make incisions in their flesh, in order to exclude the rites of idolatry. For the priests of the Gentiles shaved both head and beard, wherefore it is written (Ba 6,30): "Priests sit in their temples having their garments rent, and their heads and beards shaven." Moreover, in worshipping their idols "they cut themselves with knives and lancets" (1R 18,28). For this reason the priests of the Old Law were commanded to do the contrary.The spiritual reason for these things is that priests should be entirely free from dead works, i.e. sins. And they should not shave their heads, i.e. set wisdom aside; nor should they shave their beards, i.e. set aside the perfection of wisdom; nor rend their garments or cut their flesh, i.e. they should not incur the sin of schism.


We must now consider the duration of the ceremonial precepts: under which head there are four points of inquiry:

(1) Whether the ceremonial precepts were in existence before the Law?

(2) Whether at the time of the Law the ceremonies of the Old Law had any power of justification?

(3) Whether they ceased at the coming of Christ?

(4) Whether it is a mortal sin to observe them after the coming of Christ?

Whether the ceremonies of the Law were in existence before the Law?

Objection: 1. It would seem that the ceremonies of the Law were in existence before the Law. For sacrifices and holocausts were ceremonies of the Old Law, as stated above (Question [101], Article [4]). But sacrifices and holocausts preceded the Law: for it is written (Gn 4,3-4) that "Cain offered, of the fruits of the earth, gifts to the Lord," and that "Abel offered of the firstlings of his flock, and of their fat." Noe also "offered holocausts" to the Lord (Gn 18,20), and Abraham did in like manner (Gn 22,13). Therefore the ceremonies of the Old Law preceded the Law.
2. Further, the erecting and consecrating of the altar were part of the ceremonies relating to holy things. But these preceded the Law. For we read (Gn 13,18) that "Abraham . . . built . . . an altar to the Lord"; and (Gn 28,18) that "Jacob . . . took the stone . . . and set it up for a title, pouring oil upon the top of it." Therefore the legal ceremonies preceded the Law.
3. Further, the first of the legal sacraments seems to have been circumcision. But circumcision preceded the Law, as appears from Gn 17. In like manner the priesthood preceded the Law; for it is written (Gn 14,18) that "Melchisedech . . . was the priest of the most high God." Therefore the sacramental ceremonies preceded the Law.
4. Further, the distinction of clean from unclean animals belongs to the ceremonies of observances, as stated above (Question [100], 2, Article [6], ad 1). But this distinction preceded the Law; for it is written (Gn 7,2-3): "Of all clean beasts take seven and seven . . . but of the beasts that are unclean, two and two." Therefore the legal ceremonies preceded the Law.

On the contrary It is written (Dt 6,1): "These are the precepts and ceremonies . . . which the Lord your God commanded that I should teach you." But they would not have needed to be taught about these things, if the aforesaid ceremonies had been already in existence. Therefore the legal ceremonies did not precede the Law.
I answer that As is clear from what has been said (Question [101], Article [2]; Question [102], Article [2]), the legal ceremonies were ordained for a double purpose; the worship of God, and the foreshadowing of Christ. Now whoever worships God must needs worship Him by means of certain fixed things pertaining to external worship. But the fixing of the divine worship belongs to the ceremonies; just as the determining of our relations with our neighbor is a matter determined by the judicial precepts, as stated above (Question [99], Article [4]). Consequently, as among men in general there were certain judicial precepts, not indeed established by Divine authority, but ordained by human reason; so also there were some ceremonies fixed, not by the authority of any law, but according to the will and devotion of those that worship God. Since, however, even before the Law some of the leading men were gifted with the spirit of prophecy, it is to be believed that a heavenly instinct, like a private law, prompted them to worship God in a certain definite way, which would be both in keeping with the interior worship, and a suitable token of Christ's mysteries, which were foreshadowed also by other things that they did, according to 1Co 10,11: "All . . . things happened to them in figure." Therefore there were some ceremonies before the Law, but they were not legal ceremonies, because they were not as yet established by legislation.

Reply to Objection: 1. The patriarchs offered up these oblations, sacrifices and holocausts previously to the Law, out of a certain devotion of their own will, according as it seemed proper to them to offer up in honor of God those things which they had received from Him, and thus to testify that they worshipped God Who is the beginning and end of all.
2. They also established certain sacred things, because they thought that the honor due to God demanded that certain places should be set apart from others for the purpose of divine worship.
3. The sacrament of circumcision was established by command of God before the Law. Hence it cannot be called a sacrament of the Law as though it were an institution of the Law, but only as an observance included in the Law. Hence Our Lord said (Jn 7,20) that circumcision was "not of Moses, but of his fathers." Again, among those who worshipped God, the priesthood was in existence before the Law by human appointment, for the Law allotted the priestly dignity to the firstborn.
4. The distinction of clean from unclean animals was in vogue before the Law, not with regard to eating them, since it is written (Gn 9,3): "Everything that moveth and liveth shall be meat for you": but only as to the offering of sacrifices because they used only certain animals for that purpose. If, however, they did make any distinction in regard to eating; it was not that it was considered illegal to eat such animals, since this was not forbidden by any law, but from dislike or custom: thus even now we see that certain foods are looked upon with disgust in some countries, while people partake of them in others.

Whether, at the time of the Law, the ceremonies of the Old Law had any power of justification?

Summa Th. I-II EN Qu.102 a.6