And first of all, by the death of our Redeemer, the New Testament took the place of the Old Law which had been abolished; then the Law of Christ together with its mysteries, enactments, institutions, and sacred rites was ratified for the whole world in the blood of Jesus Christ. For, while our Divine Saviour was preaching in a restricted area — He was not sent but to the sheep that were lost of the House of Israel — the Law and the Gospel were together in force; but on the gibbet of His death Jesus made void the Law with its decrees fastened the handwriting of the Old Testament to the Cross, establishing the New Testament in His blood shed for the whole human race. “To such an extent, then,” says St. Leo the Great, speaking of the Cross of our Lord, “was there effected a transfer from the Law to the Gospel, from the Synagogue to the Church, from the many sacrifices to one Victim, that, as Our Lord expired, that mystical veil which shut off the innermost part of the temple and its sacred secret was rent violently from top to bottom.”
Pius XII, Encyclical Letter Mystici corporis Christi, no. 29 (29 June 1942).