16 Most desirable is it, and most essential, that the whole teaching of Theology should be pervaded and animated by the use of the divine Word of God. This is what the Fathers and the greatest theologians of all ages have desired and reduced to practice. It was chiefly out of the Sacred Writings that they endeavoured to proclaim and establish the Articles of Faith and the truths therewith connected, and it was in them, together with divine Tradition, that they found the refutation of heretical error, and the reasonableness, the true meaning, and the mutual relation of the truths of Catholicism. Nor will any one wonder at this who considers that the Sacred Books hold such an eminent position among the sources of revelation that without their assiduous study and use, Theology cannot be placed on its true footing, or treated as its dignity demands. For although it is right and proper that students in academies and schools should be chiefly exercised in acquiring a scientific knowledge of dogma, by means of reasoning from the Articles of Faith to their consequences, according to the rules of approved and sound philosophy - nevertheless the judicious and instructed theologian will by no means pass by that method of doctrinal demonstration which draws its proof from the authority of the Bible; "for (Theology) does not receive her first principles from any other science, but immediately from God by revelation. And, therefore, she does not receive of other sciences as from a superior, but uses them as her inferiors or handmaids."(42) It is this view of doctrinal teaching which is laid down and recommended by the prince of theologians, St. Thomas of Aquin;(43) who, moreover, shows - such being the essential character of Christian Theology - how she can defend her own principles against attack: "If the adversary," he says, "do but grant any portion of the divine revelation, we have an argument against him; thus, against a heretic we can employ Scripture authority, and against those who deny one article, we can use another. But if our opponent reject divine revelation entirely, there is then no way left to prove the Article of Faith by reasoning; we can only solve the difficulties which are raised against them."(44)' Care must be taken, then, that beginners approach the study of the Bible well prepared and furnished; otherwise, just hopes will be frustrated, or, perchance, what is worse, they will unthinkingly risk the danger of error, falling an easy prey to the sophisms and laboured erudition of the Rationalists. The best preparation will be a conscientious application to philosophy and theology under the guidance of St. Thomas of Aquin, and a thorough training therein - as We ourselves have elsewhere pointed out and directed. By this means, both in Biblical studies and in that part of Theology which is called positive, they will pursue the right path and make satisfactory progress.
Source: Providentissimus Deus (Vatican.va)