We have said that those who ultimately live in each branch of science are few. It is only by the combination in perfection of imagination and observation that success is ensured. Miller had noticed in the writer of the _Vestiges_ the absence of original observation and abstract thinking, or the power of seeing and reasoning for himself. In truth, there is something in geological speculation akin to what Professor Jebb has noticed in the field of classical emendation and of textual criticism, especially in Germany, where scholarship is a crowded profession, and eminence is often temporarily won by boldness of handling the texts. But even Ritschl, with all his heavy apparatus of learning, singularly fails in comparison with the sagacity of Bentley or the instinct of Porson. What habits of classical verse-composition had done for these scholars is brought to the geologist by observation. This, in unison with creative mental power, will alone preserve the name of the natural scientist. The first has kept White of Selborne a literary evergreen: the second has maintained his place for Cuvier. Miller's own friend, Dr. Longmuir, rightly singles out this Champollion-like trait of _sagacity_ as his most characteristic feature, by which 'he seemed by intuition to perceive what cost other minds no small amount of careful investigation.' He was very cautious in statement, and laborious in the acquisition of his data. In his works the reader will find no second-hand statements, no airy generalisation; even in fields where special research in minute departments had been by circumstances denied to him, his gift of constructive imagination often enables him to supply such defects as later investigators may have detected and added. 'The more,' says Professor Huxley, I study the fishes of the Old Red, the more I am struck by the patience and sagacity manifested in his researches, and by the natural insight which, in his case, seems to have supplied the want of special anatomical knowledge.'