Objection 1. It would seem that no suitable cause can be assigned for the ceremonies pertaining to sacrifices. For those things which were offered in sacrifice, are those which are necessary for sustaining human life: such as certain animals and certain loaves. But God needs no such sustenance; according to Psalm 49:13: "Shall I eat the flesh of bullocks? Or shall I drink the blood of goats?" Therefore such sacrifices were unfittingly offered to God.
Objection 2. Further, only three kinds of quadrupeds were offered in sacrifice to God, viz. oxen, sheep and goats; of birds, generally the turtledove and the dove; but specially, in the cleansing of a leper, an offering was made of sparrows. Now many other animals are more noble than these. Since therefore whatever is best should be offered to God, it seems that not only of these three should sacrifices have been offered to Him.
Objection 3. Further, just as man has received from God the dominion over birds and beasts, so also has he received dominion over fishes. Consequently it was unfitting for fishes to be excluded from the divine sacrifices.
Objection 4. Further, turtledoves and doves indifferently are commanded to be offered up. Since then the young of the dove are commanded to be offered, so also should the young of the turtledove.
Objection 5. Further, God is the Author of life, not only of men, but also of animals, as is clear from Genesis 1:20, seqq. Now death is opposed to life. Therefore it was fitting that living animals rather than slain animals should be offered to God, especially as the Apostle admonishes us (Romans 12:1), to present our bodies "a living sacrifice, holy, pleasing unto God."
Objection 6. Further, if none but slain animals were offered in sacrifice to God, it seems that it mattered not how they were slain. Therefore it was unfitting that the manner of immolation should be determined, especially as regards birds (Leviticus 1:15, seqq.).
Objection 7. Further, every defect in an animal is a step towards corruption and death. If therefore slain animals were offered to God, it was unreasonable to forbid the offering of an imperfect animal, e.g. a lame, or a blind, or otherwise defective animal.
Objection 8. Further, those who offer victims to God should partake thereof, according to the words of the Apostle (1 Corinthians 10:18): "Are not they that eat of the sacrifices partakers of the altar?" It was therefore unbecoming for the offerers to be denied certain parts of the victims, namely, the blood, the fat, the breastbone and the right shoulder.
Objection 9. Further, just as holocausts were offered up in honor of God, so also were the peace-offerings and sin-offerings. But no female animals was offered up to God as a holocaust, although holocausts were offered of both quadrupeds and birds. Therefore it was inconsistent that female animals should be offered up in peace-offerings and sin-offerings, and that nevertheless birds should not be offered up in peace-offerings.
Objection 10. Further, all the peace-offerings seem to be of one kind. Therefore it was unfitting to make a distinction among them, so that it was forbidden to eat the flesh of certain peace-offerings on the following day, while it was allowed to eat the flesh of other peace-offerings, as laid down in Leviticus 7:15, seqq.
Objection 11. Further, all sins agree in turning us from God. Therefore, in order to reconcile us to God, one kind of sacrifice should have been offered up for all sins.
Objection 12. Further, all animals that were offered up in sacrifice, were offered up in one way, viz. slain. Therefore it does not seem to be suitable that products of the soil should be offered up in various ways; for sometimes an offering was made of ears of corn, sometimes of flour, sometimes of bread, this being baked sometimes in an oven, sometimes in a pan, sometimes on a gridiron.
Objection 13. Further, whatever things are serviceable to us should be recognized as coming from God. It was therefore unbecoming that besides animals, nothing but bread, wine, oil, incense, and salt should be offered to God.
Objection 14. Further, bodily sacrifices denote the inward sacrifice of the heart, whereby man offers his soul to God. But in the inward sacrifice, the sweetness, which is denoted by honey, surpasses the pungency which salt represents; for it is written (Sirach 24:27): "My spirit is sweet above honey." Therefore it was unbecoming that the use of honey, and of leaven which makes bread savory, should be forbidden in a sacrifice; while the use was prescribed, of salt which is pungent, and of incense which has a bitter taste. Consequently it seems that things pertaining to the ceremonies of the sacrifices have no reasonable cause.
On the contrary, It is written (Leviticus 1:13): "The priest shall offer it all and burn it all upon the altar, for a holocaust, and most sweet savor to the Lord." Now according to Wisdom 7:28, "God loveth none but him that dwelleth with wisdom": whence it seems to follow that whatever is acceptable to God is wisely done. Therefore these ceremonies of the sacrifices were wisely done, as having reasonable causes.
I answer that, As stated above (Article 2), the ceremonies of the Old Law had a twofold cause, viz. a literal cause, according as they were intended for Divine worship; and a figurative or mystical cause, according as they were intended to foreshadow Christ: and on either hand the ceremonies pertaining to the sacrifices can be assigned to a fitting cause.
For, according as the ceremonies of the sacrifices were intended for the divine worship, the causes of the sacrifices can be taken in two ways. First, in so far as the sacrifice represented the directing of the mind to God, to which the offerer of the sacrifice was stimulated. Now in order to direct his mind to God aright, man must recognize that whatever he has is from God as from its first principle, and direct it to God as its last end. This was denoted in the offerings and sacrifices, by the fact that man offered some of his own belongings in honor of God, as though in recognition of his having received them from God, according to the saying of David (1 Chronicles 29:14): "All things are Thine: and we have given Thee what we received of Thy hand." Wherefore in offering up sacrifices man made protestation that God is the first principle of the creation of all things, and their last end, to which all things must be directed. And since, for the human mind to be directed to God aright, it must recognize no first author of things other than God, nor place its end in any other; for this reason it was forbidden in the Law to offer sacrifice to any other but God, according to Exodus 22:20: "He that sacrificeth to gods, shall be put to death, save only to the Lord." Wherefore another reasonable cause may be assigned to the ceremonies of the sacrifices, from the fact that thereby men were withdrawn from offering sacrifices to idols. Hence too it is that the precepts about the sacrifices were not given to the Jewish people until after they had fallen into idolatry, by worshipping the molten calf: as though those sacrifices were instituted, that the people, being ready to offer sacrifices, might offer those sacrifices to God rather than to idols. Thus it is written (Jeremiah 7:22): "I spake not to your fathers and I commanded them not, in the day that I brought them out of the land of Egypt, concerning the matter of burnt-offerings and sacrifices."
Now of all the gifts which God vouchsafed to mankind after they had fallen away by sin, the chief is that He gave His Son; wherefore it is written (John 3:16): "God so loved the world, as to give His only-begotten Son; that whosoever believeth in Him, may not perish, but may have life everlasting." Consequently the chief sacrifice is that whereby Christ Himself "delivered Himself... to God for an odor of sweetness" (Ephesians 5:2). And for this reason all the other sacrifices of the Old Law were offered up in order to foreshadow this one individual and paramount sacrifice--the imperfect forecasting the perfect. Hence the Apostle says (Hebrews 10:11) that the priest of the Old Law "often" offered "the same sacrifices, which can never take away sins: but" Christ offered "one sacrifice for sins, for ever." And since the reason of the figure is taken from that which the figure represents, therefore the reasons of the figurative sacrifices of the Old Law should be taken from the true sacrifice of Christ.
Reply to Objection 1. God did not wish these sacrifices to be offered to Him on account of the things themselves that were offered, as though He stood in need of them: wherefore it is written (Isaiah 1:11): "I desire not holocausts of rams, and fat of fatlings, and blood of calves and lambs and buckgoats." But, as stated above, He wished them to be offered to Him, in order to prevent idolatry; in order to signify the right ordering of man's mind to God; and in order to represent the mystery of the Redemption of man by Christ.
Reply to Objection 2. In all the respects mentioned above (ad 1), there was a suitable reason for these animals, rather than others, being offered in sacrifice to God. First, in order to prevent idolatry. Because idolaters offered all other animals to their gods, or made use of them in their sorceries: while the Egyptians (among whom the people had been dwelling) considered it abominable to slay these animals, wherefore they used not to offer them in sacrifice to their gods. Hence it is written (Exodus 8:26): "We shall sacrifice the abominations of the Egyptians to the Lord our God." For they worshipped the sheep; they reverenced the ram (because demons appeared under the form thereof); while they employed oxen for agriculture, which was reckoned by them as something sacred.
Secondly, this was suitable for the aforesaid right ordering of man's mind to God: and in two ways. First, because it is chiefly by means of these animals that human life is sustained: and moreover they are most clean, and partake of a most clean food: whereas other animals are either wild, and not deputed to ordinary use among men: or, if they be tame, they have unclean food, as pigs and geese: and nothing but what is clean should be offered to God. These birds especially were offered in sacrifice because there were plenty of them in the land of promise. Secondly, because the sacrificing of these animals represented purity of heart. Because as the gloss says on Leviticus 1, "We offer a calf, when we overcome the pride of the flesh; a lamb, when we restrain our unreasonable motions; a goat, when we conquer wantonness; a turtledove, when we keep chaste; unleavened bread, when we feast on the unleavened bread of sincerity." And it is evident that the dove denotes charity and simplicity of heart.
Thirdly, it was fitting that these animals should be offered, that they might foreshadow Christ. Because, as the gloss observes, "Christ is offered in the calf, to denote the strength of the cross; in the lamb, to signify His innocence; in the ram, to foreshadow His headship; and in the goat, to signify the likeness of 'sinful flesh' [An allusion to Colossians 2:11 (Textus Receptus)]. The turtledove and dove denoted the union of the two natures"; or else the turtledove signified chastity; while the dove was a figure of charity. "The wheat-flour foreshadowed the sprinkling of believers with the water of Baptism."
Reply to Objection 3. Fish through living in water are further removed from man than other animals, which, like man, live in the air. Again, fish die as soon as they are taken out of water; hence they could not be offered in the temple like other animals.
Reply to Objection 4. Among turtledoves the older ones are better than the young; while with doves the case is the reverse. Wherefore, as Rabbi Moses observes (Doct. Perplex. iii), turtledoves and young doves are commanded to be offered, because nothing should be offered to God but what is best.
Reply to Objection 5. The animals which were offered in sacrifice were slain, because it is by being killed that they become useful to man, forasmuch as God gave them to man for food. Wherefore also they were burnt with fire: because it is by being cooked that they are made fit for human consumption. Moreover the slaying of the animals signified the destruction of sins: and also that man deserved death on account of his sins; as though those animals were slain in man's stead, in order to betoken the expiation of sins. Again the slaying of these animals signified the slaying of Christ.
Reply to Objection 6. The Law fixed the special manner of slaying the sacrificial animals in order to exclude other ways of killing, whereby idolaters sacrificed animals to idols. Or again, as Rabbi Moses says (Doct. Perplex. iii), "the Law chose that manner of slaying which was least painful to the slain animal." This excluded cruelty on the part of the offerers, and any mangling of the animals slain.
Reply to Objection 7. It is because unclean animals are wont to be held in contempt among men, that it was forbidden to offer them in sacrifice to God: and for this reason too they were forbidden (Deuteronomy 23:18) to offer "the hire of a strumpet or the price of a dog in the house of... God." For the same reason they did not offer animals before the seventh day, because such were abortive as it were, the flesh being not yet firm on account of its exceeding softness.
Reply to Objection 8. There were three kinds of sacrifices. There was one in which the victim was entirely consumed by fire: this was called "a holocaust, i.e. all burnt." For this kind of sacrifice was offered to God specially to show reverence to His majesty, and love of His goodness: and typified the state of perfection as regards the fulfilment of the counsels. Wherefore the whole was burnt up: so that as the whole animal by being dissolved into vapor soared aloft, so it might denote that the whole man, and whatever belongs to him, are subject to the authority of God, and should be offered to Him.
Another sacrifice was the "sin-offering," which was offered to God on account of man's need for the forgiveness of sin: and this typifies the state of penitents in satisfying for sins. It was divided into two parts: for one part was burnt; while the other was granted to the use of the priests to signify that remission of sins is granted by God through the ministry of His priests. When, however, this sacrifice was offered for the sins of the whole people, or specially for the sin of the priest, the whole victim was burnt up. For it was not fitting that the priests should have the use of that which was offered for their own sins, to signify that nothing sinful should remain in them. Moreover, this would not be satisfaction for sin: for if the offering were granted to the use of those for whose sins it was offered, it would seem to be the same as if it had not been offered.
The third kind of sacrifice was called the "peace-offering," which was offered to God, either in thanksgiving, or for the welfare and prosperity of the offerers, in acknowledgment of benefits already received or yet to be received: and this typifies the state of those who are proficient in the observance of the commandments. These sacrifices were divided into three parts: for one part was burnt in honor of God; another part was allotted to the use of the priests; and the third part to the use of the offerers; in order to signify that man's salvation is from God, by the direction of God's ministers, and through the cooperation of those who are saved.
But it was the universal rule that the blood and fat were not allotted to the use either of the priests or of the offerers: the blood being poured out at the foot of the altar, in honor of God, while the fat was burnt upon the altar (Leviticus 9:9-10). The reason for this was, first, in order to prevent idolatry: because idolaters used to drink the blood and eat the fat of the victims, according to Deuteronomy 32:38: "Of whose victims they eat the fat, and drank the wine of their drink-offerings." Secondly, in order to form them to a right way of living. For they were forbidden the use of the blood that they might abhor the shedding of human blood; wherefore it is written (Genesis 9:4-5): "Flesh with blood you shall not eat: for I will require the blood of your lives": and they were forbidden to eat the fat, in order to withdraw them from lasciviousness; hence it is written (Ezekiel 34:3): "You have killed that which was fat." Thirdly, on account of the reverence due to God: because blood is most necessary for life, for which reason "life" is said to be "in the blood" (Leviticus 17:11-14): while fat is a sign of abundant nourishment. Wherefore, in order to show that to God we owe both life and a sufficiency of all good things, the blood was poured out, and the fat burnt up in His honor. Fourthly, in order to foreshadow the shedding of Christ's blood, and the abundance of His charity, whereby He offered Himself to God for us.
In the peace-offerings, the breast-bone and the right shoulder were allotted to the use of the priest, in order to prevent a certain kind of divination which is known as "spatulamantia," so called because it was customary in divining to use the shoulder-blade [spatula], and the breast-bone of the animals offered in sacrifice; wherefore these things were taken away from the offerers. This is also denoted the priest's need of wisdom in the heart, to instruct the people--this was signified by the breast-bone, which covers the heart; and his need of fortitude, in order to bear with human frailty--and this was signified by the right shoulder.
Reply to Objection 9. Because the holocaust was the most perfect kind of sacrifice, therefore none but a male was offered for a holocaust: because the female is an imperfect animal. The offering of turtledoves and doves was on account of the poverty of the offerers, who were unable to offer bigger animals. And since peace-victims were offered freely, and no one was bound to offer them against his will, hence these birds were offered not among the peace-victims, but among the holocausts and victims for sin, which man was obliged to offer at times. Moreover these birds, on account of their lofty flight, while befitting the perfection of the holocausts: and were suitable for sin-offerings because their song is doleful.
Reply to Objection 10. The holocaust was the chief of all the sacrifices: because all were burnt in honor of God, and nothing of it was eaten. The second place in holiness, belongs to the sacrifice for sins, which was eaten in the court only, and on the very day of the sacrifice (Leviticus 7:6-15). The third place must be given to the peace-offerings of thanksgiving, which were eaten on the same day, but anywhere in Jerusalem. Fourth in order were the "ex-voto" peace-offerings, the flesh of which could be eaten even on the morrow. The reason for this order is that man is bound to God, chiefly on account of His majesty; secondly, on account of the sins he has committed; thirdly, because of the benefits he has already received from Him; fourthly, by reason of the benefits he hopes to receive from Him.
Reply to Objection 11. Sins are more grievous by reason of the state of the sinner, as stated above (Question 73, Article 10): wherefore different victims are commanded to be offered for the sin of a priest, or of a prince, or of some other private individual. "But," as Rabbi Moses says (Doct. Perplex. iii), "we must take note that the more grievous the sin, the lower the species of animals offered for it. Wherefore the goat, which is a very base animal, was offered for idolatry; while a calf was offered for a priest's ignorance, and a ram for the negligence of a prince."
Reply to Objection 12. In the matter of sacrifices the Law had in view the poverty of the offerers; so that those who could not have a four-footed animal at their disposal, might at least offer a bird; and that he who could not have a bird might at least offer bread; and that if a man had not even bread he might offer flour or ears of corn.
The figurative cause is that the bread signifies Christ Who is the "living bread" (John 6:41-51). He was indeed an ear of corn, as it were, during the state of the law of nature, in the faith of the patriarchs; He was like flour in the doctrine of the Law of the prophets; and He was like perfect bread after He had taken human nature; baked in the fire, i.e. formed by the Holy Ghost in the oven of the virginal womb; baked again in a pan by the toils which He suffered in the world; and consumed by fire on the cross as on a gridiron.
Reply to Objection 13. The products of the soil are useful to man, either as food, and of these bread was offered; or as drink, and of these wine was offered; or as seasoning, and of these oil and salt were offered; or as healing, and of these they offered incense, which both smells sweetly and binds easily together.
Now the bread foreshadowed the flesh of Christ; and the wine, His blood, whereby we were redeemed; oil betokens the grace of Christ; salt, His knowledge; incense, His prayer.
Reply to Objection 14. Honey was not offered in the sacrifices to God, both because it was wont to be offered in the sacrifices to idols; and in order to denote the absence of all carnal sweetness and pleasure from those who intend to sacrifice to God. Leaven was not offered, to denote the exclusion of corruption. Perhaps too, it was wont to be offered in the sacrifices to idols.
Salt, however, was offered, because it wards off the corruption of putrefaction: for sacrifices offered to God should be incorrupt. Moreover, salt signifies the discretion of wisdom, or again, mortification of the flesh.
Incense was offered to denote devotion of the heart, which is necessary in the offerer; and again, to signify the odor of a good name: for incense is composed of matter, both rich and fragrant. And since the sacrifice "of jealousy" did not proceed from devotion, but rather from suspicion, therefore incense was not offered therein (Numbers 5:15).
Source: Summa Theologica (New Advent)