This book owes its origin to the suggestion of a friend. In conversing familiarly on the very remarkable return of some prominent Oxford divines to Catholic truth on points hitherto most violently controverted, it was observed that the great principle of justification by faith only, which Luther justly regarded as the source and essence of his whole system, was openly abandoned, and the Catholic doctrine, as expounded by the Council of Trent, admitted, with only sonle verbal distinctions and modifications, serving rather to veil the concession, than to qualify it. In these circumstances it was suggested that a candid and clear statement of Catholic faith on this important subject might be beneficial to many, whom the Oxford concessions had prepared for a more impartial examination of the question. The work of the Protestant Episcopal Bishop of Ohio subsequently came into the author's hands; on reading which he was startled by its exaggerated tone, and surprised at some misstatements of principles and misquotations of authorities, into which this prelate had been betrayed. Had the works of St. Thomas of Aquin, or the decrees of the Council of Trent been in the hands of Bishop M'Ilvaine, when he wrote his treatise, he could not have mistaken their meaning, and would not have misquoted them, as I shall show that he has done in some instances. To the same cause I feel bound to ascribe his misstatements of Catholic doctrine. The vehemence of his language, and his unmitigated denunciations of our faith may be accounted for by the pain naturally felt at seeing his Oxford brethren give us so undisputed a triumph over the Reformers in the vital principle of their revolt, which they brand with anathema as a new gospel, contrary to the everlasting Gospel of Jesus. "We are bound, therefore," says Bishop M'Ilvaine, "with regard to their divinity, as they feel bound with regard to ours by that Apostolic charge: 'Though an angel from heaven preach unto you any other gospel than that ye have received; let him be anathema.'”