It would be a fascinating task to watch these interweaving factors at their work and to trace their commingled influence as slowly their involved significance became clear, now to this man and now to that. The best narrative that has been written yet of this epochal movement is contained in Professor Bury's volume on "The Idea of Progress." There one sees the stream of this progressive conception of life pushing its way out as through a delta by way of many minds, often far separated yet flowing with the same water. Some men attacked the ancients and by comparison praised the modern time as Perrault did with "The Age of Louis the Great"; some men foresaw so clearly the possibility of man's control over nature that they dreamed of terrestrial Utopias as Francis Bacon did in "New Atlantis"; some men, like Descartes, sought to grasp the intellectual conditions of human improvement; and others, like Condorcet, became the fervid prophets of human perfectibility; some, like Turgot, re-examined history in terms of the new ideas; and some, like Saint Simon and Comte, sought to discover the law by which all progress moves. This new idea of life and history came "by divers portions and in divers manners," but no one can doubt its arrival. The life of man upon this earth was no longer conceived as static; it was progressive and the possibilities that lay ahead made all the achievements of the past seem like the play of childhood. At last, in the nineteenth century, the climactic factor was added which gathered up all the rest and embraced them in a comprehensive philosophy of life. Evolution became a credible truth. No longer a dim conjecture, it was established in biology, and then it spread its influence out into every area of human thought until all history was conceived in genetic terms and all the sciences were founded upon the evolutionary idea. Growth became recognized as the fundamental law of life. Nothing in the universe without, or in man's life within, could longer be conceived as having sprung full-statured, like Minerva from the head of Jove. All things achieved maturity by gradual processes. The world itself had thus come into being, not artificially nailed together like a box, but growing like a tree, putting forth ever new branches and new leaves. When this idea had firmly grasped the human mind, the modern age had come indeed, and progress was its distinctive category of understanding and its exhilarating phrasing of human hope. Then came the days of mid-Victorian optimism with songs like this upon men's lips: "Every tiger madness muzzled, every serpent passion kill'd, Every grim ravine a garden, every blazing desert till'd, "Robed in universal harvest up to either pole she smiles, Universal ocean softly washing all her warless isles." [11] IV