Divine ; it is unchangeable in its substance, that is to say, as in its life, its commission, and its message. It cannot in these things be either augmented or increased ; the Divine impulse of the Divine Revelation with which its Divine Creator charged it remains as eternal as Himself; more emphatically of this New Law, even than of the Old, may it be said that not one jot or tittle of it can pass away. All else may change : heaven and earth may pass away. This, then, is the first necessary statement concerning Catholicism. As the author of the following pages points out, no definition of doctrine uttered by the divine Voice of the Church on earth is in any sense whatever an addition to the original deposit of truth committed to her at the beginning ; no apparent modification or correction made by the same authority is a withdrawal of any definition previously made ; both are alike nothing more or less than a more exact form of statement of the unchangeable Creed of the Church. The Apostolic Symbol and the Creed of Pope Pius IV. are merely various assertions of the same facts. Yet presentations of these unchangeable truths do change, whether in words or ceremonies or discipline, exactly as dress changes, and exactly for the same reasons viz. : because the 263196 vi PREFACE environment and the needs of corresponding with this environ- ment changes. (The parallel is not, of course, adequate ; but it will serve.) For example, so long as men fought face to face, actual protection was more necessary than protective