THE object of the following pages is to give in a brief space an outline of the grounds of the Catholic religion. The argument presupposes three things: (I) Belief in the existence of God, the Creator of the universe and of man; (2) the spirituality of the human soul; and (3) the validity of the processes of human reason. The first two can be proved (see Bibliography at the end), although considerations of space forbid their treatment here; the third is not capable of proof, for any proof must assume and involve the conclusion. A word now as to the line followed in our treatment of the subject. The reader will not find in this book any consideration or proof of Catholic doctrines as such: the whole argument is, on the contrary, limited to the establishment, step by step, of the Church's claim to be the Religious Teacher of Mankind. Obviously, if once we prove that she is worthy of our confidence, we shall naturally be prepared to accept the doctrines she teaches. Inquirers very often begin by demanding some sort of demonstrative or intrinsic proof of a particular doctrine which they find difficult to believe; but in many cases it is impossible to give any such proof, and foolish to expect it. These doctrines do not admit of demonstration, because of their subject-matter. They are truths which are clearly seen and understood only by Almighty God and the Blessed in heaven. There these doctrines have their own intrinsic evidence; but here it is not so, for "we see now through a glass in a dark manner, but then face to face." So far as the actual proposition goes, such an article of belief is just as obscure to us, and its intrinsic truth just as invisible after our act of faith as before. The difference is this: whereas before we saw no reason for affirming or denying the truth of the proposition in question, now we have the strongest possible grounds for believing it, namely, the fact that God, to whom all truth is evident, affirms that this particular doctrine is true. We assent to it because we know that, in the words of the Catechism, God can neither deceive nor be deceived. Let us make this clear by considering one or two particular doctrines. For instance, the doctrine of priestly absolution tells us that when a priest pronounces the sacramental form, the sins of a penitent properly disposed are immediately washed away. Obviously, since no one can have direct experimental knowledge of another's soul, still less of the presence or absence of sin therein, we can have no intrinsic evidence of the truth or falsity of the doctrine in question. We assent to it as true because God says it is so, not because we see it. The same applies to the doctrine of Transubstantiation. Since substance is altogether beyond the ken of our senses, we have no positive grounds for affirming or denying the change; but when we make our act of faith, we assent to the doctrine because it comes to us on the authority of God. We cannot therefore always furnish intrinsic evidence of a Catholic dogma: what we can do is to show that it has been revealed by Almighty God, or, in other words, that the Catholic Church, our immediate teacher in these matters, is the authorized exponent of God's Revelation. Nor can it be said that assent in such a way is unreasonable. In everyday life we are continually assenting to truths of which we do not see the intrinsic evidence, but which we accept on the word of another. Everybody has heard, on the authority of science, that light travels at the rate of 186,000 miles a second, while comparatively few know the proof of this fact. But this is not necessary for a rational assent: it suffices if one takes reasonable measures to assure oneself of the trustworthiness and authority of the one who makes the statement.