Daring these years of labour in geology and zoology--interrupted only by the 'hours of idleness'--devoted to 'the species question,' Darwin, though leading at Down almost the life of a hermit, was nevertheless in frequent communication with two or three faithful friends who followed his labours with the deepest interest. Cautious as was Darwin himself, he found in his life-long friend Lyell, a still more doubting and critical spirit, and it is clear from what Darwin says that he derived much help by laying new ideas and suggestions before him. The year before Darwin's death he wrote of Lyell, 'When I made a remark to him on Geology, he never rested till he saw the whole case clearly, and often made me see it more clearly than I had done before.' Lyell's father was a botanist of considerable repute, the friend of Sir William Hooker and his distinguished son Dr (now Sir Joseph) Hooker. While Darwin was writing his _Journal of Researches_, he handed the proof-sheets to Lyell with permission to show them to his father, who was a man of great literary judgment. The elder Lyell, in turn, showed them to young Mr Hooker, who was then preparing to join Sir James Ross, in his celebrated Antarctic voyage with H.M. ships _Erebus_ and _Terror_. Hooker was then working hard to take his doctor's degree before joining the expedition as surgeon, but he kept Darwin's proof-sheets under his pillow, so as to get opportunities of reading them 'between waking and rising.' Before leaving England, however, Hooker in 1839 casually met and was introduced to Darwin, and thus commenced a friendship which resulted in such inestimable benefits to science. Before sailing with the Antarctic expedition the young surgeon received from Charles Lyell, as a parting gift, 'a copy of Darwin's _Journal_ complete'; and he tells us that the perusal stimulated in him 'an enthusiasm in the desire to travel and observe[129].' On Hooker's return from the voyage in 1843, a friendly letter from Darwin commenced that remarkable correspondence, which will always afford the best means of judging of the development of ideas in Darwin's mind. Hooker's wide knowledge of plants--especially of all questions concerning their distribution--was of invaluable assistance to Darwin, at a time when his attention was more particularly absorbed by geology and zoology, while botany had not as yet received much attention from him. Hooker's experience, gained in travel, his sound judgment and balanced mind made him a judicious adviser, while his caution and candour fitted him to become a trenchant critic of new suggestions, scarcely inferior in that respect to Lyell.