In dealing with the evolution and history of man as with that of any other animal, the first step is undoubtedly to collect the facts, and this is precisely what Lyell set out to do in the "Antiquity of Man." The first nineteen chapters of the book are purely an empirical statement of the evidence then available as to the existence of man in pre-historic times: the rest of the book is devoted to a consideration of the connection between the facts previously stated and Darwin's theory of the origin of species by variation and natural selection. The keynote of Lyell's work, throughout his life, was observation. Lyell was no cabinet geologist; he went to nature and studied phenomena at first hand. Possessed of abundant leisure and ample means he travelled far and wide, patiently collecting material and building up the modern science of physical geology, whose foundations had been laid by Hutton and Playfair. From the facts thus collected he drew his inferences, and if later researches showed these inferences to be wrong, unlike some of his contemporaries, he never hesitated to say so. Thus and thus only is true progress in science attained. Lyell is universally recognised as the leader of the Uniformitarian school of geologists, and it will be well to consider briefly what is implied in this term. The principles of Uniformitarianism may be summed up thus: THE PRESENT IS THE KEY TO THE PAST. That is to say, the processes which have gone on in the past were the same in general character as those now seen in operation, though probably differing in degree. This theory is in direct opposition to the ideas of the CATASTROPHIC school, which were dominant at the beginning of the nineteenth century. The catastrophists attributed all past changes to sudden and violent convulsions of nature, by which all living beings were destroyed, to be replaced by a fresh creation. At least such were the tenets of the extremists. In opposition to these views the school of Hutton and Lyell introduced the principle of continuity and development. There is no discrepancy between Uniformitarianism and evolution. The idea of Uniformitarianism does not imply that things have always been the same; only that they were similar, and between these two terms there is a wide distinction. Evolution of any kind whatever naturally implies continuity, and this is the fundamental idea of Lyellian geology.