“[D]eduction only is the instrument of Theology. There the simple question is, What is revealed? All doctrinal knowledge flows from one fountain head. If we are able to enlarge our view and multiply our propositions, it must be merely by the comparison and adjustment of the original truths; if we would solve new questions, it must be by consulting old answers. The notion of doctrinal knowledge absolutely novel, and of simple addition from without, is intolerable to Catholic ears, and never was entertained by any one who was even approaching to an understanding of our creed. Revelation is all in all in doctrine; the Apostles its sole depository, the inferential method its sole instrument, and ecclesiastical authority its sole sanction. The Divine Voice has spoken once for all, and the only question is about its meaning.”
John Henry Newman, The Idea of a University (1852), Discourse 9, Section 4.