(a) In both Testaments grace and the Holy Spirit are given through faith in Christ (the internal law), and doctrines, commandments and ceremonies are prescribed (the external law). But, whereas the Old Testament is principally a law of works, the New Testament is principally a law of faith (Rom., iii, 27); the former is concerned mostly with the external conduct, the latter regulates, not only actions, but also the internal movements of the soul, of which faith is the first. (b) In both Testaments men are justified and saved through faith and works (Heb, xi., 39; Rom., i. 16), and not through the external written law or the letter. But it is only through Christ, the author of the New Law, that men are enabled to perform what the law requires: “The law was given by Moses; grace and truth came by Jesus Christ” (John, i. 17). 347. Comparison of the Two Testaments from Other Viewpoints.--(a) The aim of both Laws is to secure obedience to God and holiness for man. But the New Testament, since given to those who were better prepared and more perfect, unveils more clearly the mysteries of faith, enjoins more perfect works, and supplements the Commandments with counsels of perfection (cfr. the Sermon on the Mount). (b) Both Laws make use of threats, promises and persuasion in order to move men to obedience. But, as the Old Law was for those who were spiritually but children, it dwells especially on the punishments to be meted out to transgressors and the external rewards that will be given to the obedient (the law of fear); whereas the New Law, being for those who are spiritually mature, holds out as inducements chiefly the love of virtue and rewards that are internal and spiritual (the law of love). (c) The author of both laws is God. But, while the Old Law was announced through God’s servants as the preparatory dispensation, the New Law was proclaimed by the Son of God Himself as the final economy of human salvation: “God, who at sundry times spoke in times past to the fathers by the prophets, last of all in these days hath spoken to us by His Son, whom He hath appointed heir of all things” (Heb, ii. 1). 348. Differences in the Precepts of the Two Laws.--(a) There is no opposition between the commandments of the two Laws; for the ceremonial and judicial precepts of the Old Law, which contained figure and prophecy, are fulfilled in the precepts of Christ, while the moral laws of the Old Testament are confirmed and perfected by the moral laws of Christ: “I am not come to destroy, but to fulfill” (Matt., v. 17). (b) There is no substantial difference between the faith and works of the two Testaments. For, that which is now believed explicitly and clearly, was believed implicitly and in figure in the Old Testament, and the greater things that now are commanded were contained germinally in the precepts of the Old Law.