In the autumn of 1842, two years and eight months after his marriage with his first cousin, Emma Wedgwood, who died in October last (1896), Darwin removed from London, the air and social demands of which were alike unsuited to his health, and finally fixed upon a house in the secluded village of Down, near Beckenham, where he spent the rest of his days. Henceforth the life of Darwin is merged in the books in which, from time to time, he gave the result of his long years of patient observation and inquiry, from the epoch-making Origin to the monograph on earthworms. With bad health, apparently due to gouty tendencies aggravated by chronic sea-sickness during his voyage; with nights that never gave unbroken sleep; and days that were never passed without prostrating pain; he might well have felt justified in doing nothing whatever. But he was saved from the accursed monotony of a wealthy invalid's life by his insatiate delight in searching for that solution of the problem of the mutability of species which time would not fail to bring. In this, he tells us, he forgot his "daily discomfort," and thus was delivered from morbid introspection. Darwin worked at his rough notes on the variation of animals and plants under domestication, adding facts collected by "printed enquiries, by conversations with skilful breeders and gardeners, and by extensive reading," gleams of light coming till he says that he is "almost convinced that species are not (it is like confessing a murder) immutable." But he was still groping in the dark as to the application of selection to wild plants and animals, until, as remarked above, the chance reading of Malthus suggested a working theory. A brief sketch of this theory, written out in pencil in 1842, was elaborated in 1844 into an essay of two hundred and thirty pages. The importance attached to this was shown in a letter which Darwin then addressed to his wife, charging her, in the event of his death, to apply £400 to the expense of publication. He also named certain competent men from whom an editor might be chosen, preference being given to Sir Charles (then Mr. Lyell, at whose advice Darwin began to write out his views on a scale three or four times as extensive as that in which they appeared in the Origin of Species.) Their publication in an abstract form was hastened by the receipt, in June, 1858, of a paper, containing "exactly the same theory," from Mr. Alfred Russel Wallace at Ternate in the Moluccas. This reference to that distinguished explorer, will, before the story of the coincident discovery is further told, fitly introduce a sketch of his career.