The subject of faith, although one of absorbing interest at all times, has, perhaps, in recent years, given rise to more discussion than at any time in hlstory. Differences of opinion in connexion with it at the present time turn not so much upon the truths of faith-upon what men are bound to believe and what they are to reject as upon the nature of faith itself. The great Encyclical of our Holy Father the Pope on the errors of Modernism (Pascendi) brings this fact prominently before us. Yet these errors could not have arisen if men had not previously rejected certain fundamental and supernatural truths, and amongst them the authority of the Catholic Church. If the elements which go to make up Divine faith are overlooked by the persons who discuss this question or write upon it, errors most fatal and disastrous are certain to appear, and those errors will, in many cases, be so far-reaching in their effects as ultimately to lead to the complete overthrow of all revealed religion. We have, therefore, devoted the opening chapter of the treatise to an explanation of the virtue of faith, its supernatural character, and its influence on the faculty in which it inheres. We have tried to explain how it is acquired, and the various ways in which it may be lost, and also suggested to the reader some of the differences which exist between it and the moral virtues. In referring to the nature and causes of faith we are reminded that the Vatican Council (Cap. 3, De Fide) teaches that faith is a supernatural virtue by which, under the inspiration and help of God's grace, we believe that those things which were revealed by Him are true, not because their intrinsic truth is perceived by the natural light of reason, but on account of the authority of God who reveals them and who can neither deceive nor be deceived; that to secure a reasonable assent to faith God has willed that the external arguments for revelation should be joined to the internal assistance of the Holy Spirit; and that those external arguments are, in the first place, miracles and prophecy which, since they go to demonstrate God's onmipotence and infinite knowledge, are unquestionable signs of Divine revelation and are also suited to the intellectual capacities of all.