How much of the Spiritual World is covered by Natural law we do not propose at present to inquire. It is certain, at least, that the whole is not covered. And nothing more lends confidence to the method than this. For one thing, room is still left for mystery. Had no place remained for mystery it had proved itself both unscientific and irreligious. A Science without mystery is unknown; a Religion without mystery is absurd. This is no attempt to reduce Religion to a question of mathematics, or demonstrate God in biological formulæ. The elimination of mystery from the universe is the elimination of Religion. However far the scientific method may penetrate the Spiritual World, there will always remain a region to be explored by a scientific faith. "I shall never rise to the point of view which wishes to 'raise' faith to knowledge. To me, the way of truth is to come through the knowledge of my ignorance to the submissiveness of faith, and then, making that my starting place, to raise my knowledge into faith."[18] Lest this proclamation of mystery should seem alarming, let us add that this mystery also is scientific. The one subject on which all scientific men are agreed, the one theme on which all alike become eloquent, the one strain of pathos in all their writing and speaking and thinking, concerns that final uncertainty, that utter blackness of darkness bounding their work on every side. If the light of Nature is to illuminate for us the Spiritual Sphere, there may well be a black Unknown, corresponding, at least at some points, to this zone of darkness round the Natural World. But the final gain would appear in the department of Theology. The establishment of the Spiritual Laws on "the solid ground of Nature," to which the mind trusts "which builds for aye," would offer a new basis for certainty in Religion. It has been indicated that the authority of Authority is waning. This is a plain fact. And it was inevitable. Authority--man's Authority, that is--is for children. And there necessarily comes a time when they add to the question, What shall I do? or, What shall I believe? the adult's interrogation--Why? Now this question is sacred, and must be answered. "How truly its central position is impregnable," Herbert Spencer has well discerned, "religion has never adequately realized. In the devoutest faith, as we habitually see it, there lies hidden an innermost core of scepticism; and it is this scepticism which causes that dread of inquiry displayed by religion when face to face with science."[19]