Not long ago I came across the mental experience of a working geologist which well illustrates this. "Once in early boyhood," says Mr. James E. Mills, "I left a lumberman's camp at night to go to the brook for water. It was a clear, cold, moonlight night and very still, except the distant murmuring of the Penobscot at some falls. A sense of the grandeur of the forest and rivers, the hills, and sky, and stars came over the boy, and he stood and looked around. An owl hooted, and the hooting was not a cheerful sound. The men were all asleep, and the conditions were lonely enough. But there was no feeling of loneliness; for with the sense of the grandeur of creation, came the sense, very real and strong, of the Creator's presence. In boyish imagination, I could see His almighty hand shaping the hills and scooping out the valleys, spreading the sky overhead, and making trees, animals, and men. Thirty years later I camped alone in the open air on the bank of the Gila. It was a clear, cold, moonlight night. The camp-fire was low, for the Apaches were on the warpath. An owl again hooted; but again all loneliness was dispelled by a sense of the Creator's presence, and the night of long ago by the Penobscot came into my mind, and with it the question: What is the difference to my mind between the Creator's presence now and then? To the heart, it was very like, but to the mind very different. Now, no great hand was shaping things from without. But God was everywhere, reaching down through long lines of forces, and shaping and sustaining things from within. I had been travelling all day by mountains of lava which had cooled long ages ago, and over grounds which the sea, now far off, had left on its beaches; and with the geologist's habit recalled the lava still glowing and flowing, and the sea still rolling its pebbles on the beaches. But now I knew it was by forces within the earth that the lava was poured out, and that the waves which rolled the pebbles were driven by the wind and the wind by the sun's heat. And the forces within the earth and the heat within the sun come from still further within. Inward, always inward, the search for the original energy and law carried my mind, for He whose will is the source of all force, and whose thought is the source of all law is on the inside of the universe. The kingdom of God is within you."