The authority of other Catholic interpreters is not so grave. Since, however, the study of Scripture has always continued to advance in the Church, their commentaries also have their own honorable place, and are serviceable in many ways for the refutation of assailants and the unravelling of difficulties. It is, moreover, most unbecoming to pass by, in ignorance or contempt, the splendid works which our own scholars have left behind them in abundance, and to have recourse to the works of the heterodox, and to seek in them, with peril to sound doctrine and not seldom with detriment to faith, the explanation of passages on which Catholics have long ago most excellently expended their talents and their labor. Although the studies of the heterodox, used with prudence, may sometimes be of use to the Catholic interpreter, he should nevertheless bear well in mind this repeated testimony of the ancients,--that the sense of the Sacred Scriptures can nowhere be found incorrupt outside the Church, and that it cannot be delivered by those who, being destitute of the true faith, only gnaw the husk of Scripture and never reach its marrow. Most desirable it is, and most essential, that the whole course of Theology should be pervaded by the use of the Divine Scripture, which should be, as it were, the soul thereof. This is what the Fathers and the greatest theologians of all ages have professed and practised. It was chiefly out of the sacred writings that they endeavored to proclaim and establish the Articles of Faith and the truths which are their consequences. 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 the Catholic faith. Nor will any one wonder at this who considers that the Sacred Books hold such a pre-eminent position among the sources of Revelation that without the assiduous study of them Theology cannot be rightly treated as its dignity demands. Although it is right and proper that students in academical institutions 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 solid philosophy, nevertheless a grave and learned theologian will by no means overlook that method of doctrinal demonstration which draws its proof from the authority of the Bible. Theology does not receive her first principles from other sciences, but immediately from God through Revelation. And therefore she does not receive from other sciences as from superiors, but uses them as her inferiors and her handmaids. It is this view of doctrinal teaching which is laid down and recommended by the prince of theologians, St. Thomas of Aquin. He also shows--such being the essential character of Christian Theology--how a theologian can defend his own principles against attack.