In some respects, there was an extraordinary resemblance in their modes and habits of thought, between Lyell and Darwin; and this likeness was also seen in their modesty, their deference to the opinion of younger men, their enthusiasm for science, their freedom from petty jealousies and their righteous indignation for what was mean and unworthy in others. But yet there was a difference. Both Lyell and Darwin were cautious, but perhaps Lyell carried his caution to the verge of timidity. I think Darwin possessed, and Lyell lacked, what I can only describe by the theological term, "faith--the substance of things hoped for, the evidence of things not seen." Both had been constrained to feel that the immutability of species could not be maintained. Both, too, recognised the fact that it would be useless to proclaim this conviction, unless prepared with a satisfactory alternative to what Huxley called "the Miltonic hypothesis." But Darwin's conviction was so far vital and operative that it sustained him while working unceasingly for twenty-two years in collecting evidence bearing on the question, till at last he was in the position of being able to justify that conviction to others.
And yet Lyell's attitude--and that of Hooker, which was very similar--proved of inestimable service to science, as Darwin often acknowledged.
One of the greatest merits of the "Origin of Species" is that so many difficulties and objections are anticipated and fairly met; and this was to a great extent the result of the persistent and very candid--if always friendly--criticism of Lyell and Hooker.
I think the divergence of mental attitude in Lyell and Darwin must be attributed to a difference in temperament, the evidence of which sometimes appears in a very striking manner in their correspondence. Thus in 1838, while they were in the thick of the fight with the Catastrophists of the Geological Society, Lyell wrote characteristically: "I really find, when bringing up my Preliminary Essays in "Principles" to the science of the present day, so far as I know it, that the great outline, and even most of the details, stand so uninjured, and in many cases they are so much strengthened by new discoveries, especially by yours, that we may begin to hope that the great principles there insisted on will stand the test of new discoveries." (Lyell's "Life, Letters and Journals", Vol. II. page 44.)To which the more youthful and impetuous Darwin replies: "BEGIN TO HOPE: why the POSSIBILITY of a doubt has never crossed my mind for many a day.
This may be very unphilosophical, but my geological salvation is staked on it...it makes me quite indignant that you should talk of HOPING." ("L.L."I. page 296.)
It was not only Darwin's "geological salvation" that was at stake, when he surrendered himself to his enthusiasm for an idea. To his firm faith in the doctrine of continuity we owe the "Origin of Species"; and while Darwin became the "Paul" of evolution, Lyell long remained the "doubting Thomas."Many must have felt like H.C. Watson when he wrote: "How could Sir C.
Lyell...for thirty years read, write, and think, on the subject of species AND THEIR SUCCESSION, and yet constantly look down the wrong road!" ("L.L."II. page 227.) Huxley attributed this hesitation of Lyell to his "profound antipathy" to the doctrine of the "pithecoid origin of man." ("L.L." II. page 193.) Without denying that this had considerable influence (and those who knew Lyell and his great devotion to his wife and her memory, are aware that he and she felt much stronger convictions concerning such subjects as the immortality of the soul than Darwin was able to confess to) yet I think Darwin had divined the real characteristics of his friend's mind, when he wrote: "He would advance all possible objections...AND EVEN AFTER THESEWERE EXHAUSTED, WOULD REMAIN LONG DUBIOUS."