I answer that, As stated above (A[1]), the New Law is compared to the Old as the perfect to the imperfect. Now everything perfect fulfils that which is lacking in the imperfect. And accordingly the New Law fulfils the Old by supplying that which was lacking in the Old Law.
Now two things of every law is to make men righteous and virtuous, as was stated above (Q[92], A[1]): and consequently the end of the Old Law was the justification of men. The Law, however, could not accomplish this: but foreshadowed it by certain ceremonial actions, and promised it in words. And in this respect, the New Law fulfils the Old by justifying men through the power of Christ's Passion. This is what the Apostle says ( Rom. 8:3 , 4 ): "What the Law could not do . . . God sending His own Son in the likeness of sinful flesh . . . hath condemned sin in the flesh, that the justification of the Law might be fulfilled in us." And in this respect, the New Law gives what the Old Law promised, according to 2 Cor. 1:20 : "Whatever are the promises of God, in Him," i.e. in Christ, "they are 'Yea'." [*The Douay version reads thus: "All the promises of God are in Him, 'It is'."] Again, in this respect, it also fulfils what the Old Law foreshadowed. Hence it is written ( Col. 2:17 ) concerning the ceremonial precepts that they were "a shadow of things to come, but the body is of Christ"; in other words, the reality is found in Christ. Wherefore the New Law is called the law of reality; whereas the Old Law is called the law of shadow or of figure.
Now Christ fulfilled the precepts of the Old Law both in His works and in His doctrine. In His works, because He was willing to be circumcised and to fulfil the other legal observances, which were binding for the time being; according to Gal. 4:4 : "Made under the Law." In His doctrine He fulfilled the precepts of the Law in three ways. First, by explaining the true sense of the Law. This is clear in the case of murder and adultery, the prohibition of which the Scribes and Pharisees thought to refer only to the exterior act: wherefore Our Lord fulfilled the Law by showing that the prohibition extended also to the interior acts of sins. Secondly, Our Lord fulfilled the precepts of the Law by prescribing the safest way of complying with the statutes of the Old Law. Thus the Old Law forbade perjury: and this is more safely avoided, by abstaining altogether from swearing, save in cases of urgency. Thirdly, Our Lord fulfilled the precepts of the Law, by adding some counsels of perfection: this is clearly seen in Mat. 19:21, where Our Lord said to the man who affirmed that he had kept all the precepts of the Old Law: "One thing is wanting to thee: If thou wilt be perfect, go, sell whatsoever thou hast," etc. [*St. Thomas combines Mat. 19:21 with Mk. 10:21 ].
Reply to Objection 1: The New Law does not void observance of the Old Law except in the point of ceremonial precepts, as stated above (Q[103], AA[3],4). Now the latter were figurative of something to come. Wherefore from the very fact that the ceremonial precepts were fulfilled when those things were accomplished which they foreshadowed, it follows that they are no longer to be observed: for it they were to be observed, this would mean that something is still to be accomplished and is not yet fulfilled. Thus the promise of a future gift holds no longer when it has been fulfilled by the presentation of the gift. In this way the legal ceremonies are abolished by being fulfilled.
Reply to Objection 2: As Augustine says (Contra Faust. xix, 26), those precepts of Our Lord are not contrary to the precepts of the Old Law. For what Our Lord commanded about a man not putting away his wife, is not contrary to what the Law prescribed. "For the Law did not say: 'Let him that wills, put his wife away': the contrary of which would be not to put her away. On the contrary, the Law was unwilling that a man should put away his wife, since it prescribed a delay, so that excessive eagerness for divorce might cease through being weakened during the writing of the bill. Hence Our Lord, in order to impress the fact that a wife ought not easily to be put away, allowed no exception save in the case of fornication." The same applies to the prohibition about swearing, as stated above. The same is also clear with respect to the prohibition of retaliation. For the Law fixed a limit to revenge, by forbidding men to seek vengeance unreasonably: whereas Our Lord deprived them of vengeance more completely by commanding them to abstain from it altogether. With regard to the hatred of one's enemies, He dispelled the false interpretation of the Pharisees, by admonishing us to hate, not the person, but his sin. As to discriminating between various foods, which was a ceremonial matter, Our Lord did not forbid this to be observed: but He showed that no foods are naturally unclean, but only in token of something else, as stated above (Q[102], A[6], ad 1).
Reply to Objection 3: It was forbidden by the Law to touch a leper; because by doing so, man incurred a certain uncleanness of irregularity, as also by touching the dead, as stated above (Q[102], A[5], ad 4). But Our Lord, Who healed the leper, could not contract an uncleanness. By those things which He did on the sabbath, He did not break the sabbath in reality, as the Master Himself shows in the Gospel: both because He worked miracles by His Divine power, which is ever active among things; and because He worked miracles by His Divine power, which is ever active among things; and because His works were concerned with the salvation of man, while the Pharisees were concerned for the well-being of animals even on the sabbath; and again because on account of urgency He excused His disciples for gathering the ears of corn on the sabbath. But He did seem to break the sabbath according to the superstitious interpretation of the Pharisees, who thought that man ought to abstain from doing even works of kindness on the sabbath; which was contrary to the intention of the Law.
Reply to Objection 4: The reason why the ceremonial precepts of the Law are not mentioned in Mat. 5 is because, as stated above (ad 1), their observance was abolished by their fulfilment. But of the judicial precepts He mentioned that of retaliation: so that what He said about it should refer to all the others. With regard to this precept, He taught that the intention of the Law was that retaliation should be sought out of love of justice, and not as a punishment out of revengeful spite, which He forbade, admonishing man to be ready to suffer yet greater insults; and this remains still in the New Law.
Whether the New Law is contained in the Old?
Objection 1: It would seem that the New Law is not contained in the Old. Because the New Law consists chiefly in faith: wherefore it is called the "law of faith" ( Rom. 3:27 ). But many points of faith are set forth in the New Law, which are not contained in the Old. Therefore the New Law is not contained in the Old.
Objection 2: Further, a gloss says on Mat. 5:19, "He that shall break one of these least commandments," that the lesser commandments are those of the Law, and the greater commandments, those contained in the Gospel. Now the greater cannot be contained in the lesser. Therefore the New Law is not contained in the Old.
Objection 3: Further, who holds the container holds the contents. If, therefore, the New Law is contained in the Old, it follows that whoever had the Old Law had the New: so that it was superfluous to give men a New Law when once they had the Old. Therefore the New Law is not contained in the Old.
On the contrary, As expressed in Ezech. 1:16, there was "a wheel in the midst of a wheel," i.e. "the New Testament within the Old," according to Gregory's exposition.
I answer that, One thing may be contained in another in two ways. First, actually; as a located thing is in a place. Secondly, virtually; as an effect in its cause, or as the complement in that which is incomplete; thus a genus contains its species, and a seed contains the whole tree, virtually. It is in this way that the New Law is contained in the Old: for it has been stated (A[1]) that the New Law is compared to the Old as perfect to imperfect. Hence Chrysostom, expounding Mk. 4:28, "The earth of itself bringeth forth fruit, first the blade, then the ear, afterwards the full corn in the ear," expresses himself as follows: "He brought forth first the blade, i.e. the Law of Nature; then the ear, i.e. the Law of Moses; lastly, the full corn, i.e. the Law of the Gospel." Hence then the New Law is in the Old as the corn in the ear.
Reply to Objection 1: Whatsoever is set down in the New Testament explicitly and openly as a point of faith, is contained in the Old Testament as a matter of belief, but implicitly, under a figure. And accordingly, even as to those things which we are bound to believe, the New Law is contained in the Old.
Reply to Objection 2: The precepts of the New Law are said to be greater than those of the Old Law, in the point of their being set forth explicitly. But as to the substance itself of the precepts of the New Testament, they are all contained in the Old. Hence Augustine says (Contra Faust. xix, 23,28) that "nearly all Our Lord's admonitions or precepts, where He expressed Himself by saying: 'But I say unto you,' are to be found also in those ancient books. Yet, since they thought that murder was only the slaying of the human body, Our Lord declared to them that every wicked impulse to hurt our brother is to be looked on as a kind of murder." And it is in the point of declarations of this kind that the precepts of the New Law are said to be greater than those of the Old. Nothing, however, prevents the greater from being contained in the lesser virtually; just as a tree is contained in the seed.
Reply to Objection 3: What is set forth implicitly needs to be declared explicitly. Hence after the publishing of the Old Law, a New Law also had to be given.
Whether the New Law is more burdensome than the Old?
Objection 1: It would seem that the New Law is more burdensome than the Old. For Chrysostom (Opus Imp. in Matth., Hom. x [*The work of an unknown author]) say: "The commandments given to Moses are easy to obey: Thou shalt not kill; Thou shalt not commit adultery: but the commandments of Christ are difficult to accomplish, for instance: Thou shalt not give way to anger, or to lust." Therefore the New Law is more burdensome than the Old.
Objection 2: Further, it is easier to make use of earthly prosperity than to suffer tribulations. But in the Old Testament observance of the Law was followed by temporal prosperity, as may be gathered from Dt. 28:1-14 ; whereas many kinds of trouble ensue to those who observe the New Law, as stated in 2 Cor. 6:4-10 : "Let us exhibit ourselves as the ministers of God, in much patience, in tribulation, in necessities, in distresses," etc. Therefore the New Law is more burdensome than the Old.
Objection 3: The more one has to do, the more difficult it is. But the New Law is something added to the Old. For the Old Law forbade perjury, while the New Law proscribed even swearing: the Old Law forbade a man to cast off his wife without a bill of divorce, while the New Law forbade divorce altogether; as is clearly stated in Mat. 5:31, seqq., according to Augustine's expounding. Therefore the New Law is more burdensome than the Old.
On the contrary, It is written ( Mat. 11:28 ): "Come to Me, all you that labor and are burdened": which words are expounded by Hilary thus: "He calls to Himself all those that labor under the difficulty of observing the Law, and are burdened with the sins of this world." And further on He says of the yoke of the Gospel: "For My yoke is sweet and My burden light." Therefore the New Law is a lighter burden than the Old.
I answer that, A twofold difficult may attach to works of virtue with which the precepts of the Law are concerned. One is on the part of the outward works, which of themselves are, in a way, difficult and burdensome. And in this respect the Old Law is a much heavier burden than the New: since the Old Law by its numerous ceremonies prescribed many more outward acts than the New Law, which, in the teaching of Christ and the apostles, added very few precepts to those of the natural law; although afterwards some were added, through being instituted by the holy Fathers. Even in these Augustine says that moderation should be observed, lest good conduct should become a burden to the faithful. For he says in reply to the queries of Januarius (Ep. lv) that, "whereas God in His mercy wished religion to be a free service rendered by the public solemnization of a small number of most manifest sacraments, certain persons make it a slave's burden; so much so that the state of the Jews who were subject to the sacraments of the Law, and not to the presumptuous devices of man, was more tolerable."
The other difficulty attaches to works of virtue as to interior acts: for instance, that a virtuous deed be done with promptitude and pleasure. It is this difficulty that virtue solves: because to act thus is difficult for a man without virtue: but through virtue it becomes easy for him. In this respect the precepts of the New Law are more burdensome than those of the Old; because the New Law prohibits certain interior movements of the soul, which were not expressly forbidden in the Old Law in all cases, although they were forbidden in some, without, however, any punishment being attached to the prohibition. Now this is very difficult to a man without virtue: thus even the Philosopher states (Ethic. v, 9) that it is easy to do what a righteous man does; but that to do it in the same way, viz. with pleasure and promptitude, is difficult to a man who is not righteous. Accordingly we read also ( 1 Jn. 5:3 ) that "His commandments are not heavy": which words Augustine expounds by saying that "they are not heavy to the man that loveth; whereas they are a burden to him that loveth not."
Reply to Objection 1: The passage quoted speaks expressly of the difficulty of the New Law as to the deliberate curbing of interior movements.
Reply to Objection 2: The tribulations suffered by those who observe the New Law are not imposed by the Law itself. Moreover they are easily borne, on account of the love in which the same Law consists: since, as Augustine says (De Verb. Dom., Serm. lxx), "love makes light and nothing of things that seem arduous and beyond our power."