Excerpted from Dei Verbum: Dogmatic Constitution on Divine Revelation, the Catholic Church's 1965 document on sacred scripture.

...The books of both the Old and New Testaments in their entirety, with all their parts, are sacred and canonical because written under the inspiration of the Holy Spirit, they have God as their author and have been handed on as such to the Church herself. In composing the sacred books, God chose men and while employed by Him they made use of their powers and abilities, so that with Him acting in them and through them, they, as true authors, consigned to writing everything and only those things which He wanted. Therefore, since everything asserted by the inspired authors or sacred writers must be held to be asserted by the Holy Spirit, it follows that the books of Scripture must be acknowledged as teaching solidly, faithfully and without error that truth which God wanted put into sacred writings for the sake of salvation. ... To search out the intention of the sacred writers, attention should be given, among other things, to "literary forms." For truth is set forth and expressed differently in texts which are variously historical, prophetic, poetic, or of other forms of discourse. The interpreter must investigate what meaning the sacred writer intended to express and actually expressed in particular circumstances by using contemporary literary forms in accordance with the situation of his own time and culture. For the correct understanding of what the sacred author wanted to assert, due attention must be paid to the customary and characteristic styles of feeling, speaking and narrating which prevailed at the time of the sacred writer, and to the patterns men normally employed at that period in their everyday dealings with one another. But, since Holy Scripture must be read and interpreted in the sacred spirit in which it was written, no less serious attention must be given to the content and unity of the whole of Scripture if the meaning of the sacred texts is to be correctly worked out. ...It is the task of exegetes to work according to these rules toward a better understanding and explanation of the meaning of Sacred Scripture, so that through preparatory study the judgment of the Church may mature. The plan of salvation foretold by the sacred authors, recounted and explained by them, is found as the true word of God in the books of the Old Testament: these books, therefore, written under divine inspiration, remain permanently valuable. "For all that was written for our instruction, so that by steadfastness and the encouragement of the Scriptures we might have hope" (Rom. 15:4).

... Now the books of the Old Testament, in accordance with the state of mankind before the time of salvation established by Christ, reveal to all men the knowledge of God and of man and the ways in which God, just and merciful, deals with men. These books, though they also contain some things which are incomplete and temporary, nevertheless show us true divine pedagogy. These same books, then, give expression to a lively sense of God, contain a store of sublime teachings about God, sound wisdom about human life, and a wonderful treasury of prayers, and in them the mystery of our salvation is present in a hidden way. Christians should receive them with reverence.

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.