While Darwin doubtless derived his inspiration, and much valuable aid, from the _Principles of Geology_, and its gifted author, yet Lyell, with all his clearness of vision, logical faculty and literary skill, did not possess the strong faith and resolute courage--to say nothing of that wonderful tenacity of purpose and power of research which were such striking characteristics of Darwin--which would have enabled him to do for the organic what he did for the inorganic world. If it be true, as Darwin used to suggest, that the _Origin of Species_ might never have been written had not Lyell first produced the _Principles of Geology_, I believe it is no less certain that the crowning of Lyell's great edifice, by the full application of his principles to the world of living beings, could only have been accomplished by a man possessing, in unique combination, the powers of observation, experiment, reasoning and criticism, joined to unswerving determination, which distinguished Darwin. Starting from Lyell's most advanced post, Darwin boldly advanced into regions in which his friend was unable to lead, and indeed long hesitated to follow. Together, for nearly forty years, the two men--influencing one another 'as iron sharpeneth iron'--thought and communed and worked, aided at all times by the wide knowledge and judicious criticism of the sagacious Hooker; and together the fame of these men will go down to posterity. There is a tendency, when a great man has passed from our midst, to estimate his merits and labours with undiscriminating, and often perhaps exaggerated, admiration; and this excessive praise is too often followed by a reaction, as the result of which the idol of one generation becomes almost commonplace to the next. A still further period is required before the proper position of mental perspective is reached by us, and a just judgment can be formed of the man's real place in history. The reputations of both Lyell and Darwin have, I think, passed through both these two earlier phases of thought, and we may have arrived at the third stage. There was one respect in which both Lyell and Darwin failed to satisfy many both of their contemporaries and successors. Lyell, like Hutton, always deprecated attempts to go back to a 'beginning,' while Darwin, who strongly supported Lyell in his geological views, was equally averse to speculations concerning the 'origin of life on the globe.' Scrope[146], and also Huxley[147] in his earlier days, held the opinion that it was legitimate to assume or imagine a beginning, from which, with ever diminishing energy, the existing 'comparatively quiet conditions,' thought to characterise the present order of the world, would be reached. Both Lyell and Darwin insisted that geology is a historical science, and must be treated as such quite distinct from Cosmogony. And in the end, Huxley accepted the same view[148]. 'Geology,' he asserted, 'is as much a historical science as archaeology.'