In these days when there is a strong movement on foot without the fold, to restore the unity of the Christian faith, we can indulge the hope that the four lectures of the distinguished Abbot will prove fruitful. They are on subjects so vital to unity; _i. e._ the Supremacy of the Pope, the Sacrifice of the Mass, the Eternal Priesthood, the Universal Church. We pray that these sermons will attract the attention of many outside the Church, and make them meditate on the bitterness of breaking from their "Father's House." May God's holy grace prove stronger than prejudice, as it has so often in the past, and may it soften the hearts which have been hardened by cruel legislation rather than by wilful disobedience. JOHN CARDINAL FARLEY, _Archbishop of New York_. NEW YORK, The Feast of St. Thomas the Apostle, 1913 CONTENTS I THE POPE'S AUTHORITY II THE HOLY MASS III THE PRIESTHOOD IV THE CHURCH BY LAW ESTABLISHED BOOKS SUGGESTED FOR READING I I THE POPE'S AUTHORITY TO-DAY we begin the work of Advent. During these weeks of preparation for the great feast of Christmas it is usual and useful to turn our thoughts to some of the great principles upon which our faith as Catholics is grounded, in order that we may realise more fully all that our Blessed Lord's coming into this world has done for mankind in general and for our individual souls in particular. It will not therefore be altogether foreign to this purpose if during these Sundays of Advent I ask your consideration of certain Catholic principles which appear to me to have been deliberately abandoned in the great religious revolution of the sixteenth century, known as the Reformation, but to which our Catholic forefathers in England and in Ireland clung with heroic constancy and for which they suffered loss of worldly goods and even laid down their lives.