"Of the Law of the Gospel, Called the New Law, Considered in Itself
Whether the New Law is a written law?
Objection 1. It would seem that the New Law is a written law. For the New Law is just the same as the Gospel. But the Gospel is set forth in writing, according to Jn. 20:31: "But these are written that you may believe." Therefore the New Law is a written law.
Objection 2. Further, the law that is instilled in the heart is the natural law, according to Rm. 2:14,15: "(The Gentiles) do by nature those things that are of the law . . . who have [Vulg.: 'show'] the work of the law written in their hearts." If therefore the law of the Gospel were instilled in our hearts, it would not be distinct from the law of nature.
Objection 3. Further, the law of the Gospel is proper to those who are in the state of the New Testament. But the law that is instilled in the heart is common to those who are in the New Testament and to those who are in the Old Testament: for it is written (Wis. 7:27) that Divine Wisdom "through nations conveyeth herself into holy souls, she maketh the friends of God and prophets." Therefore the New Law is not instilled in our hearts.
On the contrary, The New Law is the law of the New Testament. But the law of the New Testament is instilled in our hearts. For the Apostle, quoting the authority of Jeremias 31:31,33: "Behold the days shall come, saith the Lord; and I will perfect unto the house of Israel, and unto the house of Judah, a new testament," says, explaining what this statement is (Heb. 8:8,10): "For this is the testament which I will make to the house of Israel . . . by giving [Vulg.: 'I will give'] My laws into their mind, and in their heart will I write them." Therefore the New Law is instilled in our hearts.
I answer that, "Each thing appears to be that which preponderates in it," as the Philosopher states (Ethic. ix, 8). Now that which is preponderant in the law of the New Testament, and whereon all its efficacy is based, is the grace of the Holy Ghost, which is given through faith in Christ. Consequently the New Law is chiefly the grace itself of the Holy Ghost, which is given to those who believe in Christ. This is manifestly stated by the Apostle who says (Rm. 3:27): "Where is . . . thy boasting? It is excluded. By what law? Of works? No, but by the law of faith": for he calls the grace itself of faith "a law." And still more clearly it is written (Rm. 8:2): "The law of the spirit of life, in Christ Jesus, hath delivered me from the law of sin and of death." Hence Augustine says (De Spir. et Lit. xxiv) that "as the law of deeds was written on tables of stone, so is the law of faith inscribed on the hearts of the faithful": and elsewhere, in the same book (xxi): "What else are the Divine laws written by God Himself on our hearts, but the very presence of His Holy Spirit?"
Nevertheless the New Law contains certain things that dispose us to receive the grace of the Holy Ghost, and pertaining to the use of that grace: such things are of secondary importance, so to speak, in the New Law; and the faithful need to be instructed concerning them, both by word and writing, both as to what they should believe and as to what they should do. Consequently we must say that the New Law is in the first place a law that is inscribed on our hearts, but that secondarily it is a written law.
Reply to Objection 1. The Gospel writings contain only such things as pertain to the grace of the Holy Ghost, either by disposing us thereto, or by directing us to the use thereof. Thus with regard to the intellect, the Gospel contains certain matters pertaining to the manifestation of Christ's Godhead or humanity, which dispose us by means of faith through which we receive the grace of the Holy Ghost: and with regard to the affections, it contains matters touching the contempt of the world, whereby man is rendered fit to receive the grace of the Holy Ghost: for "the world," i.e. worldly men, "cannot receive" the Holy Ghost (Jn. 14:17). As to the use of spiritual grace, this consists in works of virtue to which the writings of the New Testament exhort men in divers ways.
Reply to Objection 2. There are two ways in which a thing may be instilled into man. First, through being part of his nature, and thus the natural law is instilled into man. Secondly, a thing is instilled into man by being, as it were, added on to his nature by a gift of grace. In this way the New Law is instilled into man, not only by indicating to him what he should do, but also by helping him to accomplish it.
Reply to Objection 3. No man ever had the grace of the Holy Ghost except through faith in Christ either explicit or implicit: and by faith in Christ man belongs to the New Testament. Consequently whoever had the law of grace instilled into them belonged to the New Testament.
Whether the New Law justifies?
Objection 1. It would seem that the New Law does not justify. For no man is justified unless he obeys God's law, according to Heb. 5:9: "He," i.e. Christ, "became to all that obey Him the cause of eternal salvation." But the Gospel does not always cause men to believe in it: for it is written (Rm. 10:16): "All do not obey the Gospel." Therefore the New Law does not justify.
Objection 2. Further, the Apostle proves in his epistle to the Romans that the Old Law did not justify, because transgression increased at its advent: for it is stated (Rm. 4:15): "The Law worketh wrath: for where there is no law, neither is there transgression." But much more did the New Law increase transgression: since he who sins after the giving of the New Law deserves greater punishment, according to Heb. 10:28,29: "A man making void the Law of Moses dieth without any mercy under two or three witnesses. How much more, do you think, he deserveth worse punishments, who hath trodden underfoot the Son of God," etc.? Therefore the New Law, like the Old Law, does not justify.
Objection 3. Further, justification is an effect proper to God, according to Rm. 8:33: "God that justifieth." But the Old Law was from God just as the New Law. Therefore the New Law does not justify any more than the Old Law.
On the contrary, The Apostle says (Rm. 1:16): "I am not ashamed of the Gospel: for it is in the power of God unto salvation to everyone that believeth." But there is no salvation but to those who are justified. Therefore the Law of the Gospel justifies.
I answer that, As stated above (1), there is a twofold element in the Law of the Gospel. There is the chief element, viz. the grace of the Holy Ghost bestowed inwardly. And as to this, the New Law justifies. Hence Augustine says (De Spir. et Lit. xvii): "There," i.e. in the Old Testament, "the Law was set forth in an outward fashion, that the ungodly might be afraid"; "here," i.e. in the New Testament, "it is given in an inward manner, that they may be justified." The other element of the Evangelical Law is secondary: namely, the teachings of faith, and those commandments which direct human affections and human actions. And as to this, the New Law does not justify. Hence the Apostle says (2 Cor. 3:6) "The letter killeth, but the spirit quickeneth": and Augustine explains this (De Spir. et Lit. xiv, xvii) by saying that the letter denotes any writing external to man, even that of the moral precepts such as are contained in the Gospel. Wherefore the letter, even of the Gospel would kill, unless there were the inward presence of the healing grace of faith.
Reply to Objection 1. This argument holds true of the New Law, not as to its principal, but as to its secondary element: i.e. as to the dogmas and precepts outwardly put before man either in words or in writing.
Reply to Objection 2. Although the grace of the New Testament helps man to avoid sin, yet it does not so confirm man in good that he cannot sin: for this belongs to the state of glory. Hence if a man sin after receiving the grace of the New Testament, he deserves greater punishment, as being ungrateful for greater benefits, and as not using the help given to him. And this is why the New Law is not said to "work wrath": because as far as it is concerned it gives man sufficient help to avoid sin.
Reply to Objection 3. The same God gave both the New and the Old Law, but in different ways. For He gave the Old Law written on tables of stone: whereas He gave the New Law written "in the fleshly tables of the heart," as the Apostle expresses it (2 Cor. 3:3). Wherefore, as Augustine says (De Spir. et Lit. xviii), "the Apostle calls this letter which is written outside man, a ministration of death and a ministration of condemnation: whereas he calls the other letter, i.e. the Law of the New Testament, the ministration of the spirit and the ministration of justice: because through the gift of the Spirit we work justice, and are delivered from the condemnation due to transgression." Thomas Aquinas (1225-1274), Summa Theologica, found here courtesy the English Dominicans
While on holidays recently I happened across an old post from 2010 on David Schutz's blog (link in blogroll) wherein he declared that the Lutheran distinction between Law and Gospel was not part of the catholic tradition but was an innovation. In a way, David is correct: there was not enough understanding or practice of the proper distinction between Law and Gospel in the early and medieval church. That deficit led directly to the Reformation. But that there were no precedents for the Lutheran distinction between Law and Gospel in the catholic tradition prior to the Reformation is not true. The Lutheran doctrine is a deepening of a discussion on Law and Gospel which can be traced through the catholic tradition back to its roots in the New Testament writings, where it was occasioned by the conflict in the apostolic church with the Judaizers. This conflict brought about the inspired reflections on the relation between the Old and New covenants and the relation of Law and the Gospel under the New covenant, a theme which, when it is not being discussed openly, is never far beneath the surface of the New Testament (witness Jesus' encounters with sinners in the Gospels, which teach the distinction between Law and Gospel in a most practical manner).
On to Aquinas: while Aquinas's terminology above is not Lutheran (we would not normally refer to the Gospel as "the new Law" for fear of misunderstanding, although such terminology can be used and understood in a correct manner, hence the apostle Paul's "law of faith" language) his content here, I maintain, is consistent with later Luther expositions of the relation between Law and Gospel. For that reason, this passage serves as a good example of the necessity of carefully examining what a theologian actually says, even if his terminology is appears unfamiliar or even erroneous, rather than being content to do theology by slogans.
Having said that, what does Aquinas actually say here? There are three chief things I am interested in and draw your attention to. the first thing is that the "law" of the Gospel is the principle of grace, which is given by the Holy Spirit who justifies the ungodly through faith. In Lutheran theology we would naturally agree, and we would therefore say that the Gospel - the good news that we are saved by grace through faith alone in Christ alone - must predominate on the preaching and teaching of the church.
The second thing is that God's Law, as given in the Old Testament on tablets of stone, did not have the power to justify but only to terrify. Lutherans would again agree. In Lutheran terms this is called the theological use of the law, i.e. the Law accuses the sinner and leads to a knowledge of his sins, and it is still operative in the lives of believers in as much as we remain sinners after justification (the "old Adam").
The third thing is that such aspects of the "new law" or Gospel as doctrines and commandments or precepts do not justify - since justification comes by faith and not the law. So, we are not justified by believing in the doctrine of justification by faith alone, rather, we are justified by believing in Christ. By the same token, neither are we justified by believing in the infallibility of the Pope, the immaculate conception and assumption of the virgin Mary, or any of the other doctrines which Rome has declared to be de fide (of the faith) and therefore necessary for salvation. That's not to say that doctrine is not important! Doctrine (specifically the doctrine of the Gospel; see the doctrinal articles of the Augsburg Confession) is essential, but as a means to an end, not the end itself.
To note all of this is not to say that Aquinas was a proto-Lutheran. Not only would that be anachronistic, but Aquinas's soteriological notions, conceived under the influence of Aristotle, whereby grace is a substance infused into man's soul which, with the consent of the subject's free will, moves the soul towards God as its highest good through the cultivation of the virtues (hence Aquinas's statement that "we work justice") are not just questionable but unBiblical. The Lutheran can at least take consolation from the fact that Aquinas taught that the justification of the ungodly was greater miracle than sanctification - this is why Lutheran insist on the primacy of the article of justification in the hierarchy of doctrines.
In Aquinas's defense, it could be said that he was attempting to show that the then newly re-discovered thought of Aristotle (whom Aquinas simply refers to as "the Philosopher"), which presented quite a challenge to the church, was not antithetic to the Christian faith. Unfortunately Aquinas went beyond merely apologetic concerns and allowed the thought categories of Aristotle to shape his theology in a way which finally distorted Christian doctrine (a similar path was trodden by those theologians of the 20th century who used Existentialism for apologetic and explanatory purposes).
Thus the tragedy of modern Roman Catholicism, which has made Aquinas its official theologian for all time (which is why Lutherans should study him; the informed reader can see his influence everywhere in the 1992 Catechism of the Catholic Church for e.g.). By doing so, the Roman church has canonised not only the truths which Aquinas sets forth, but also his errors.