So through the sixties and seventies the battle for evolution went merrily on, and before Darwin’s death in 1881 it was evident that the scientific world was largely converted and still more evident that the theory had taken solid hold upon the popular mind. Even in the sixties Charles Kingsley could write to F. D. Maurice: ‘The state of the scientific mind is most curious; Darwin is conquering everywhere, and rushing in like a flood, by the mere force of truth and fact.’[380] Darwin himself was no aggressive fighter, though perhaps his quiet, persistent, logical statement of facts went further than fighting. But he had fighting followers, and they pushed his cause with an energy and dogmatism which he himself could hardly have manifested. In England Spencer gave the theory the metaphysical and philosophical sanction and support which Darwin was not equipped to render, and the brilliant, ardent eloquence of Huxley paralyzed opponents with incisive argument and stinging ridicule. In America Asa Gray, the great botanist, was a convert from the beginning and a most helpful disciple, and his aid was peculiarly welcome to Darwin, because Gray’s eager orthodoxy was useful in conciliating many whose prejudices would naturally have been most adverse. Darwin repeatedly spoke of Gray as understanding his ideas better and expounding them more effectively than almost any one. John Fiske was also a valuable champion from the more philosophical side. In Germany Weisman and Häckel were the most prominent apostles, and immensely effective, though, with thorough-going Teutonic logic, they were ready to push conclusions to lengths that were not always acceptable to Darwin himself. The amount of popular interest is probably best shown in the extensive sale of Darwin’s books. ‘The Origin of Species’ was successful at once. It went through edition after edition, in Darwin’s lifetime six in all, and was translated into numerous foreign languages. The later books, even those of a more technical character, sold like popular fiction, and the last one, on the apparently uninviting subject of earthworms, found many readers everywhere.