How far will [human beings] go? Three hundred years of scientific method have built the great sky-touching buildings and nourished the incalculable fertility of the human species. But man is also homo duplex, as they knew in the darker ages. He partakes of evil and of good, of god and of man. Both struggle in him perpetually. And he is himself a flame—a great, roaring, wasteful furnace devouring irreplaceable substances of the earth.