Then came the greatest of books on the development of living things. In 1859, Darwin gave the world his “Origin of Species,” a work which laid the foundation of the science of evolution. Earlier thinkers had groped and guessed with little knowledge of Nature’s laws. But Darwin had discovered the laws of organic life, and, with an amazing array of evidential facts patiently observed and gathered in a score of years, he was able to support his view that species have been evolved “by means of natural selection” through “the preservation or favored races in the struggle of life.” In the interest of the six-days creation legend, a storm of theological wrath assailed the great man’s head. Knowing that truth was on his side, the saint of science paid no heed to slander and patiently worked on. And in twenty-three years he wrought a greater, a more farreaching revolution in the thoughts of intelligent mankind than was ever accomplished by any other of the sons of men; and when he died, England was glad to honor his dust with burial in her sacred Westminster Abbey. Evolution is as firmly established to-day as the fact of gravitation. The intellect of the whole world acclaims it as the one and only principle that explains the phenomena of existence. True it is, that many naturalists disagree with Darwin with respect to some of the details of the _process_ by which evolution has been brought about, but these men are one and all thoroughgoing evolutionists. There is no man of science living who believes in special creation. Every university now teaches evolution. Every science studies its facts to-day, in the light of growth and change from simplicity to complexity. The astronomer traces the course of evolution in the heavens; the geologist follows the path of evolution in the crust of the earth; the biologist threads the process of growth through succeeding forms of life; the psychologist considers the gradual emergence of mind from the lowly animal to civilized man; the sociologist elucidates the progressive development of society from its rude barbaric dawn; the inquiries of the anthropologist illuminate the evolution of religion, of government, of law. Every phase of existence and life and thought opens its treasury of secrets when touched by evolution’s master key. Where all the facts point resistlessly to one conclusion, that conclusion must perforce be accepted as true. The foundations of evolution are laid in all the active phenomena of nature and the super-structure is being fashioned by all the facts of growth and change. The purpose of this little book is to set before the busy reader some of the principal facts illustrating the evolution of the universe and of living things. MARSHALL J. GAUVIN Pittsburgh, Pa., August 30, 1921. List of Illustrations