In the first place, coal will not give out for a long, long time. In the second place, its disappearance will not make the slightest difference, for in the few cubic inches of the human brain nature has stored up treasures greater than all those hidden in the depths of the earth. The creation of the human brain took more years than the creation of the coal fields, but the brain's resources are inexhaustible. A German workman now comes along who has discovered a chemical substitute for coal, better than coal in many ways, and before this German shall have been dead many years some other will find a further substitute far better and cheaper than his. There is endless heat power in the action of the tides, in the rush of Niagara, in the winds, and in endless chemical combinations. Heat is motion, and the Universe is motion. Men will soon cease lighting tiny bonfires to obtain crude heat in a crude way. Electricity or the sun's own rays, concentrated for heating purposes, will do the work without any digging in mines by men, or delving in ashes and clinkers by women. The story of antiquity, more or less fictitious, of the burning of a fleet with the aid of a glass and the sunbeams, will be matter-of-fact reality long before the coal shall have been exhausted. HOW THE OTHER PLANETS WILL TALK TO US We talk of civilization as though it necessarily implied improvement. Civilization means the school and the library, but it also means the prison and the poorhouse. Two short stories illustrate different views of what we call civilization: Aristippus was a young Greek gentleman of large means, genuine intellectual power, a sense of humor and a reputation as a philosopher. He was on his way to Corinth with a young lady named Lais, or possibly he was coming from Corinth with her. Anyhow, he was wrecked on the voyage. If you know anything about the reputation of Lais, you know that the philosopher was badly employed, and that the Greek gods doubtless wrecked his vessel to impress upon his mind the importance of morality. Thrown ashore on a barren stretch of sand, the philosopher was very sad at first. He observed on the sand the remains of certain geometrical drawings, and instantly exclaimed: "There is help near. Here I see signs of thinking men, of civilization." ---- Voltaire tells of wrecked individuals thrown on a lonely coast, and also much distressed and frightened. They saw no geometrical tracings in the sand. But on a bleak moor in the twilight they saw the black beams of a gibbet, and below the cross-piece, swinging in the wind, they saw a human skeleton with bony wrists and ankles chained together. Prayerfully the wanderers dropped on their knees and exclaimed with upturned eyes: "Thank God, we have got back to civilization." ----