Now in such a universal parliament we see what the Church of Rome essentially is, viewed from her natural side. She is ideally, if not actually, the parliament of the believing world. Her doctrines, as she one by one unfolds them, emerge upon us like petals from a half-closed bud. They are not added arbitrarily from without; they are developed from within. They are the flowers contained from the first in the bud of our moral consciousness. When she formulates in these days something that has not been formulated before, she is no more enunciating a new truth than was Newton when he enunciated the theory of gravitation. Whatever truths, hitherto hidden, she may in the course of time grow conscious of, she holds that these were always implied in her teaching, though before she did not know it; just as gravitation was implied in many ascertained facts that men knew well enough long before they knew that it was implied in them. Thus far, then, the Church of Rome essentially is the spiritual sense of humanity, speaking to men through its proper and only possible organ. Its intricate machinery, such as its systems of representation, its methods of voting, the appointment of its speaker, and the legal formalities required in the recording of its decrees, are things accidental only; or if they are necessary, they are necessary only in a secondary way. But the picture of the Church thus far is only half drawn. She is all this, but she is something more than this. She is not only the parliament of spiritual man, but she is such a parliament guided by the Spirit of God. The work of that Spirit may be secret, and to the natural eyes untraceable, as the work of the human will is in the human brain. But none the less it is there. _Totam infusa per artus Mens agitat molem, et magno se corpore miscet._ The analogy of the human brain is here of great help to us. The human brain is an arrangement of material particles which can become connected with consciousness only in virtue of such a special arrangement. The Church is theoretically an arrangement of individuals which can become connected with the Spirit of God only in virtue of an arrangement equally special. If this be a true picture of the Catholic Church, and the place which the only revelation we are concerned with ideally holds in the world, there can be no _a priori_ difficulty in the passage from a natural religion to such a supernatural one. The difficulties begin when we compare the ideal picture with the actual facts; and it is true, when we do this, that they at once confront us with a strength that seems altogether disheartening. These difficulties are of two distinct kinds; some, as in the case of natural theism, are moral; others are historical. We will deal with the former first, beginning with that which is at once the profoundest and the most obvious.