16 God, the inspirer and author of both Testaments, wisely arranged that the New Testament be hidden in the Old and the Old be made manifest in the New. For, though Christ established the new covenant in His blood (see Luke 22:20; 1 Cor. 11:25), still the books of the Old Testament with all their parts, caught up into the proclamation of the Gospel, acquire and show forth their full meaning in the New Testament (see Matt. 5:17; Luke 24:27; Rom. 16:25-26; 2 Cor. 14:16) and in turn shed light on it and explain it.
Source: Dei Verbum (Vatican.va)