Editing Development of Darwin's theory (section)

===Essay===
[[Image:Gower Street London.jpg|thumb|The Darwins lived in [[Gower Street (London)|Gower Street]] in London.]]
[[File:Approaching Down House - geograph.org.uk - 1196017.jpg|thumb|In 1842 they moved to [[Down House]] in rural [[Kent]].]]
They returned on 18 July to a London seething with [[Chartism|Chartist]] unrest, and Darwin copied and scribbled changes to his "Sketch" until it was almost illegible. He returned to house hunting and found a former parsonage in the rural hamlet of [[Downe]] at a good price. A general strike led to huge demonstrations all over London, but was crushed by troops by the time Darwin moved. On 17 September 1842 the family moved into [[Down House]] (around 1850 the village changed its name to Downe to avoid confusion with [[County Down]] in Ireland, but the house kept the old spelling). After a series of alterations Darwin settled in, and in 1843 returned to writing his ''Volcanic Islands''. In May he began a (mostly geological) country diary he called ''The General Aspect''.

In response to a request from [[George Robert Waterhouse]] for advice on classification, Darwin replied that it properly "consists in grouping beings according to their actual ''relationship'', ie their consanguinity, or descent from common stocks".<ref name="Letter 684">{{Citation | title=Letter 684 – Darwin, C. R. to Waterhouse, G. R. (26 July 1843)| publisher =Darwin Correspondence Project | url=http://www.darwinproject.ac.uk/entry-684 | access-date=9 February 2016}}</ref> He followed this up with another letter expressing belief that "all the orders, families & genera amongst the Mammals are merely artificial terms highly useful to show the relationship of those members of the series, ''which have not become extinct''",  before cautiously asking for the letter to be returned.<ref name="Letter 685">{{Citation | title=Letter 685 – Darwin, C. R. to Waterhouse, G. R. (31 July 1843) | publisher =Darwin Correspondence Project | url=http://www.darwinproject.ac.uk/entry-685 | access-date=9 February 2016}}</ref> Waterhouse was influenced by Owen and in a paper attacked such heresies, setting his species in the symbolic circles of the [[Quinarian system]], not hereditary trees.{{sfn|Desmond|Moore|1991|pp=310–312}} Darwin sent a sharp response about these "vicious circles".<ref name="Letter 718">{{Citation | title=Letter 718 – Darwin, C. R. to Waterhouse, G. R. (3 or 17 Dec 1843)| publisher=Darwin Correspondence Project | url=http://www.darwinproject.ac.uk/entry-718 | access-date=9 February 2016}}</ref>

Darwin became a close friend of the botanist [[Joseph Dalton Hooker]], and on 11 January 1844 wrote to with melodramatic humour that he was "almost convinced (quite contrary to opinion I started with) that species are not (it is like confessing a murder) immutable. Heaven forfend me from Lamarck nonsense of a "tendency to progression" “adaptations from the slow willing of animals" &c,—but the conclusions I am led to are not widely different from his—though the means of change are wholly so— I think I have found out (here's presumption!) the simple way by which species become exquisitely adapted to various ends."<ref>{{Citation | title = Letter 729 – Darwin, C. R. to Hooker, J. D., (11 Jan 1844) | url = http://www.darwinproject.ac.uk/darwinletters/calendar/entry-729.html | publisher = Darwin Correspondence Project | access-date = 10 October 2009 }}</ref> Hooker's reply was cautious but friendly, saying that "There may in my opinion have been a series of productions on different spots, & also a gradual change of species. I shall be delighted to hear how you think that this change may have taken place, as no presently conceived opinions satisfy me on the subject."<ref>{{Citation | title = Letter 734 – Hooker, J. D. to Darwin, C. R., 29 Jan 1844 | url = http://www.darwinproject.ac.uk/darwinletters/calendar/entry-734.html | publisher = Darwin Correspondence Project | access-date = 10 October 2009 }}</ref>

Darwin worked up his "Sketch" into a 189-page '"Essay"' and in July entrusted the manuscript to the local schoolmaster to copy. He then wrote a difficult letter to be opened by his wife in the event of his death requesting that the essay be published posthumously. He started his ''Geological Observations on South America'', and corresponded with Hooker about this, feeding in questions related to his "Essay". The copied "Essay", now 231 pages, was returned to him for corrections in September. Then one day he brought it to Emma and asked her to read it. She went through the pages, making notes in the margins pointing out unclear passages and showing where she disagreed.

The Reverend [[Leonard Jenyns]], a naturalist Darwin had known since his time at the [[University of Cambridge]], had at Darwin's request contributed the volume on ''Fish'' in ''[[Zoology of the Voyage of H.M.S. Beagle]]'', and was now working on a book of notes on observations of plants and animals. On 12 October Darwin wrote to tell him that "work on the species question has impressed me very forcibly with the importance of all such works, as your intended one, containing what people are pleased generally to call trifling facts. These are the facts, which make one understand the working or œconomy of nature&nbsp;.... namely what are the checks & what the periods of life, by which the increase of any given species is limited." He told Jenyns that he had "continued steadily reading & collecting facts on variation of domestic animals & plants & on the question of what are species; I have a grand body of facts & I think I can draw some sound conclusions. The general conclusion at which I have slowly been driven from a directly opposite conviction is that species are mutable & that allied species are co-descendants of common stocks. I know how much I open myself, to reproach, for such a conclusion, but I have at least honestly & deliberately come to it. I shall not publish on this subject for several years."<ref>{{Citation | title =Letter 782 – Darwin, C. R. to Jenyns, Leonard, 12 Oct (1844) | url =http://www.darwinproject.ac.uk/darwinletters/calendar/entry-782.html | publisher =Darwin Correspondence Project | access-date =9 October 2009 | archive-url =https://web.archive.org/web/20070901014041/http://www.darwinproject.ac.uk/darwinletters/calendar/entry-782.html | archive-date =1 September 2007 | url-status =dead }}</ref> In November he thanked Jenyns for sending a detailed note, and told him "With respect to my far-distant work on species, I must have expressed myself with singular inaccuracy, if I led you to suppose that I meant to say that my conclusions were inevitable. They have become so, after years of weighing puzzles, to myself alone;; but in my wildest day-dream, I never expect more than to be able to show that there are two sides to the question of the immutability of species, ie whether species are directly created, or by intermediate laws, (as with the life & death of individuals)." He outlined the events that had led him to these ideas, and while cautious about "numerous immense difficulties on my notions" told him that he had "drawn up a sketch & had it copied (in 200 pages) of my conclusions; & if I thought at some future time, that you would think it worth reading, I shd. of course be most thankful to have the criticism of so competent a critic."<ref>{{Citation | title = Letter 793 – Darwin, C. R. to Jenyns, Leonard, 25 (Nov 1844) | url = http://www.darwinproject.ac.uk/darwinletters/calendar/entry-793.html | archive-url = https://archive.today/20120731183252/http://www.darwinproject.ac.uk/darwinletters/calendar/entry-793.html | url-status = dead | archive-date = 31 July 2012 | publisher = Darwin Correspondence Project | access-date = 9 October 2009 }}</ref> Jenyns never took up this offer to read the "Essay", but did advise Darwin on possible issues with the term "mutation". Darwin replied "it will be years before I publish, so that I shall have plenty of time to think of better words".<ref>{{Citation | title = Letter 828 – Darwin, C. R. to Jenyns, Leonard, 14 Feb (1845) | url = http://www.darwinproject.ac.uk/darwinletters/calendar/entry-828.html | archive-url = https://archive.today/20120729163834/http://www.darwinproject.ac.uk/darwinletters/calendar/entry-828.html | url-status = dead | archive-date = 29 July 2012 | publisher = Darwin Correspondence Project | access-date = 9 October 2009 }}</ref>