'Along with Malthus I had read, and been even more deeply impressed by, Sir Charles Lyell's immortal _Principles of Geology_; which had taught me that the inorganic world--the whole surface of the earth, its seas and lands, its mountains and valleys, its rivers and lakes, and every detail of its climatic conditions--were and always had been in a continual state of slow modification. Hence it became obvious that the forms of life must have become continually adjusted to these changed conditions in order to survive. The succession of fossil remains throughout the whole geological series of rocks is the record of the change; and it became easy to see that the extreme slowness of these changes was such as to allow ample opportunity for the continuous automatic adjustment of the organic to the inorganic world, as well as of each organism to every other organism in the same area, by the simple processes of "variation and survival of the fittest." Thus was the fundamental idea of the "origin of species" logically formulated from the consideration of a series of well ascertained facts[75].' Nor were the two men (who, like Aaron and Hur so steadily sustained the hands of Darwin in his long vigil), behind the two authors of Natural Selection themselves in their devotion to Lyell. How touching is Hooker's tribute of affection on the death of his friend, 'My loved, my best friend, for well nigh forty years of my life. To me the blank is fearful, for it never will, never can be filled up. The most generous sharer of my own and my family's hopes, joys, and sorrows, whose affection for me was truly that of a father and brother combined[76].' And Huxley speaking of Lyell, the day after his death said, 'Sir Charles Lyell would be known in history as the greatest geologist of his time. Some days ago I went to my venerable friend, and put before him the results of the _Challenger_ expedition. Nothing could then have been more touching than the conflict between the mind and the material body, the brain clear and comprehending all; while the lips could hardly express the views which the busy mind formed[77].' How well do I recollect my last visit to Lyell a day or two after this farewell interview with Huxley, the glow of gratitude which lighted up the noble features as with trembling lips he told me how 'Huxley had repeated his whole Royal Institution lecture at his bedside.' Huxley was a most devoted student of Lyell. Speaking to his fellow geologists in 1869 he said, 'Which of us has not thumbed every page of the _Principles of Geology_[78]?' and writing in 1887 on the reception of the _Origin of Species_, he said:--