It's well-known that, in 1831, Adam Sedgwick, Professor of Geology at Cambridge, President of the Geological Society and one of the great figures of "the heroic age of geology," took Charles Darwin on a short, but highly educational and influential, geological fieldtrip in Wales. Darwin received his invitation to join the Beagle expedition immediately afterwards, and so Sedgwick set the foundations for Darwin's geologizing. It was John Stevens Henslow, Professor of Mineralogy and Botany at Cambridge and a lifelong friend of Darwin who arranged the trip, and it was to Henslow that Darwin wrote from Rio de Janeiro in 1832:
Tell Prof: Sedgwick he does not know how much I am indebted to him for the Welch expedition.— it has given me an interest in geology, which I would not give up for any consideration.— I do not think I ever spent a more delightful three weeks, than in pounding the NW mountains.
The circumstances of the "Welch expedition" are puzzling in many ways. While he had been interested in mineralogy as a child, Darwin was turned off geology while at Edinburgh, having found the lectures "incredibly dull" and the science questionable; it seems that he did not attend Sedgwick's lectures while an undergraduate at Cambridge. Sedgwick was a strong character and a man of outspoken opinions, many of which would not have resonated with the young Charles Darwin. The detailed discussion of the expedition by Paul Barrett makes fascinating reading (see reference below).
Darwin and Sedgwick did not subsequently correspond at any length, but their letters were cordial - until the publication of The Origin of Species. On the 24th November, 1859, Sedgwick wrote a letter to Darwin that, in spite of being signed "your true-hearted old friend," was extremely blunt:
If I did not think you a good tempered & truth loving man I should not tell you that, (spite of the great knowledge; store of facts; capital views of the corelations of the various parts of organic nature; admirable hints about the diffusions, thro' wide regions, of nearly related organic beings; &c &c) I have read your book with more pain than pleasure. Parts of it I admired greatly; parts I laughed at till my sides were almost sore; other parts I read with absolute sorrow; because I think them utterly false & grievously mischievous
............. I have written in a hurry & in a spirit of brotherly love. Therefore forgive any sentence you happen to dislike; & believe me, spite of our disagreement in some points of the deepest moral interest, your true-hearted old friend A. Sedgwick.
On the 26th November, Darwin replied:
My dear Prof. Sedgwick
I did not at all expect that you would have written to me.— You could not possibly have paid me a more honourable compliment than in expressing freely your strong disapprobation of my Book.— I fully expected it. I can only say that I have worked like a slave on the subject for above 20 years & am not conscious that bad motives have influenced the conclusions at which I have arrived. I grieve to have shocked a man whom I sincerely honour. But I do not think you would wish anyone to conceal the results at which he has arrived after he has worked, according to the best ability which may be in him. I do not think my book will be mischievous; for there are so many workers that, if I be wrong I shall soon be annihilated; & surely you will agree that truth can be known only by rising victorious from every attack.
I daresay I may have written too confidently from feeling so confident of the truth of my main doctrine. I have made already a few converts of good & tried naturalists & oddly enough two of them compliment me on my cautious mode of expression! This will make you laugh. My notion of young men being best judges of new doctrines was not invented for occasion; for however erroneous, I remember nearly twenty years ago laughing with Lyell over the idea.— I have tried to be honest in giving all the many & grave difficulties which occurred to me, or I met in published works. I cannot think a false theory would explain so many classes of facts, as the theory seems to me to do. But magna est veritas & thank God, prevalebit.
Forgive me for scribbling at such length, & let me say again how I grieved I am to have encountered your severe disapprobation & ridicule. Your kind & noble heart shows itself throughout your letter. I thank you for writing, & remain with sincere respect | Yours truly obliged
Joseph Dalton Hooker was a leading botanist and palaeobotanist who worked on Darwin's collection after the Beagle voyage and played a leading role in supporting the development and the publication of The Origin of Species; he was probably the first high-profile scientific figure to publicly support Darwin's theory, and shared the abuse. In 1860, after leading traditional botanists had attacked Hooker, Darwin wrote to his old friend:
How paltry it is in such men as Balfour, Arnott & Co. not reading your Essay. It is incredibly paltry.— They may all attack me to their hearts' content. I am got case-hardened. As for the old fogies in Cambridge it really signifies nothing. I look at their attacks, as a proof that our work is worth the doing. It makes me resolve to buckle on my armour.— I see plainly that it will be a long uphill fight.— But think of Lyell's progress with geology.— One thing I see most plainly that without Lyell, yours, Huxley & Carpenter's aid my book would have been a mere flash in the pan.— But if we all stick to it, we shall surely gain the day. And I now see that the battle is worth fighting. I deeply hope that you think so.
Among "the old fogies in Cambridge" was Adam Sedgwick.
[Barrett, Paul H. 1974. The Sedgwick-Darwin geologic tour of North Wales. Proceedings of the American Philosophical Society 118, No. 2. (19 April): 146-164. Available online at http://darwin-online.org.uk/pdf/1974_Wales_F1964.pdf; The Sedgwick Museum in Cambridge will be hosting a major exhibition, Darwin the Geologist, this summer - http://www.sedgwickmuseum.org/ and http://www.darwin2009.cam.ac.uk/.]