If anyone should meditate with devotion and perspicacity on the sermon our Lord gave on the mount, as we read in the Gospel of Saint Matthew, he will doubtless find there . . . the perfect way of the Christian life.... This sermon contains ... all the precepts needed to shape one's life. 20
Catechism number 1968
The Law of the Gospel fulfills the commandments of the Law. the Lord's Sermon on the Mount, far from abolishing or devaluing the moral prescriptions of the Old Law, releases their hidden potential and has new demands arise from them: it reveals their entire divine and human truth. It does not add new external precepts, but proceeds to reform the heart, the root of human acts, where man chooses between the pure and the impure,22 where faith, hope, and charity are formed and with them the other virtues. the Gospel thus brings the Law to its fullness through imitation of the perfection of the heavenly Father, through forgiveness of enemies and prayer for persecutors, in emulation of the divine generosity.23