The coming of Christ was not to destroy, but to fulfill. Hence our Lord never in any way abrogated the moral teaching of the Old Law. Whatever Moses had declared to the people as the moral code of Israel was never to be slackened, but rather, under the New Dispensation of love (for which men had been laboriously trained and educated under centuries of fear), to be filled out in fuller detail. The Commandments were not, therefore, to be lessened, but to be increased. Whatever had been ordained was still ordained; what had been at one time permitted, might not, however, be permitted now. All this is the inevitable result of a higher grade of holiness. As the soul draws nearer and nearer to the holiness of God, it absorbs more and more of the meaning of sanctity. Things that at one time seemed hardly to suggest a scruple now become considered in a new light, from a higher plane. The soul has become more sensitive, and can detect flaws and defects where before it would have noticed nothing amiss. As we get holier, we think ourselves always worse, for always more pronounced is the great gulf fixed between what we are and what we should be. And what I can see taking place in my own soul, has taken place in a larger way in the upward movement of the race towards God. Before, Moses forbade adultery; but now, "I say that whosoever lusteth after a woman in his heart hath already committed adultery." The New Law thus fills in the details of the Old.
It is interesting to see, as a result of this, that without Christianity man would have no real proof of the idea of racial progress. Destroy or deny the truth of Christian teaching and nothing can be found to show any advance on our part towards the "perfect day." The whole doctrine of progress rests upon a supposition that man has grown towards a larger and freer hope. Christianity alone, especially Catholic Christianity, can ratify and confirm this. Abolish our idea of a Redemption accomplished and our notion that Christ introduced new laws and a new sacrifice and new channels of grace through the Sacraments, and the whole fabric supporting progress falls to the ground. Apart from the advance made by Christianity upon both Judaism and Paganism, there is very little evidence of an upward movement; for neither in art, nor even in crafts, have we - considering the length of time the human race has occupied the earth - made progress. It is difficult for us to improve on the masterpieces of ancient art or literature: and even in technical skill some of the builders of antiquity were ahead of us. We are simply unable nowadays, with all our resources, to do what some of them have done. Doubtless we have discovered things they did not know, but also how many things have we not forgotten? The note, therefore, of optimism that pervades modern scientific circles rests upon the moral teaching of Christianity.
This, too, is enforced by the Commandments. The new interpretation which Christ has given to the Old Law, the spiritualizing influence which He has shed on what was to a certain extent a material view of moral life, are all advances which will be made noticeable to anyone who will take the trouble to study them severally. He cannot but be struck by the huge advance in ethical values which has been made in this New Dispensation. Under the previous code, the whole relationship of God to man in the matters of moral life was a relationship of rewards and punishments. Was man obedient, then he would be rewarded: was he suffering, then had he done evil and was but fittingly punished. But the new code meant, in some ways, a reversing of the old. Suffering and success were now proofs neither of rewards nor of punishments, but of love only. Whatever happens, I am now to find love as the sole solution of life and its problems. I am not to be searching my heart to see wherein I have failed, but rejoicing myself that in all God is showing me His love. The Commandments come, indeed, as restraints to human nature, but as restraints that impose the burden of love. "Decline from evil" is the least and lowest act of religion, the highest and best is "Do good." Man was created, not to avoid sin, but to love God; and we show that love - so He has taught us, not by calling upon His Name, but by keeping His Commandments.
- text taken from by Father Bede Jarrett, O.P.