At the start of 1863, Charles Darwin was actively working on the manuscript of The variation of animals and plants under domestication, anticipating with excitement the construction of a hothouse to accommodate his increasingly varied botanical experiments, and continuing a massive scientific correspondence. Six months later the volume of his correspondence dropped markedly, reflecting a decline in his already weak health. Although Darwin worried about the effect of the quarrels on public perceptions, his theory was gathering support in influential scientific circles. He struggled with leaf angles, fractions, diagrams, and shoot dissections.

1862 was a particularly productive year for Darwin. This was not only the case in his published output (two botanical papers and a book on the pollination mechanisms of orchids), but more particularly in the extent and breadth of the botanical experiments he carried out. While many of these remained unpublished for several years, they formed the foundation of numerous later publications. The promotion of his theory of natural selection also continued: Darwin’s own works expanded on it, Thomas Henry Huxley gave lectures about it, and Henry Walter Bates invoked it to explain mimicry in butterflies.  

Darwin's first known letters were written when he was twelve. They continue through school-days at Shrewsbury, two years as a medical student at Edinburgh University, the undergraduate years at Cambridge, and the of the voyage of H.M.S. Beagle. Letters exchanged with family and friends give a vivid picture of the social life of the Shropshire gentry of the 1820s and 1830s. In the earliest letters Darwin was already keenly interested in natural history. During the voyage of H.M.S. Beagle Darwin’s letters convey the excitement and enthusiasm of a keen and careful collector let loose in a new and challenging land. 

The year 1874 was one of consolidation, reflection, and turmoil for Darwin. He spent the early months working on second editions of Coral reefs and Descent of man; the rest of the year was mostly devoted to further research on insectivorous plants. A vicious dispute over an anonymous review that attacked the work of Darwin’s son George dominated the second half of the year. His children were growing up: Horace began an engineering apprenticeship, Leonard joined the transit of Venus expedition to New Zealand, and Francis married Amy Ruck and became his father's secretary.

Having laboured for nearly five years on human evolution, sexual selection, and the expression of emotions, Darwin was able to devote 1873 almost exclusively to his beloved plants. He resumed work on the digestive powers of sundews and Venus fly traps, and the comparative fertility and vigour of self- and cross-pollinated species, work that would culminate in two books, Insectivorous plants (1875) and Cross and self fertilisation (1876). Darwin’s son Francis became increasingly involved in this botanical research, eventually renouncing plans for a medical career to become his father’s scientific secretary.

On 7 January 1860, John Murray published the second edition of Darwin’s Origin of species, printing off another 3000 copies to satisfy the demands of an audience that surprised both the publisher and the author. It wasn't long, however, before ‘the stones began to fly’. Members of the scientific community found many difficulties in Origin in the year after its publication and Darwin despaired of making his ideas understood. Among these problems was that arising from the implications it had for human ancestry, hotly debated at the famous meeting of the British Association in Oxford that summer.

The years 1858 and 1859 were, without doubt, the most momentous of Darwin’s life. From a quiet rural existence filled with steady work on his ‘big book’ on species, he was jolted into action by the arrival of an unexpected letter from Alfred Russel Wallace. This letter led to the first announcement of Darwin’s and Wallace’s respective theories of organic change at the Linnean Society of London in July 1858 and prompted the composition and publication, in November 1859, of Darwin’s major treatise On the origin of species by means of natural selection. By the end of 1859, Darwin’s work was being discussed in publications as diverse as The Times and the English Churchman, and Darwin himself was busy as never before: answering letters, justifying and explaining his views to friends, relations, and ‘bitter opponents’. The correspondence shows vividly just how distressed Darwin was during the days leading up to the Linnean meeting. On 18 June 1858, his eldest daughter, Henrietta Emma,  was stricken with diphtheria, then a little-known and frightening illness. Several days later, their 18-month-old baby, Charles Waring, came down with scarlet fever. His condition deteriorated rapidly in the space of a few days and the Darwins were shocked by his unexpected death on 28 June.

The year was marked by three deaths of personal significance to Darwin: Hugh Falconer, a friend and supporter; Robert FitzRoy, captain of the Beagle; and William Jackson Hooker, director of the Royal Botanic Gardens, Kew, and father of Darwin’s friend Joseph Hooker’s father. There was also a serious dispute between two of Darwin’s friends, John Lubbock and Charles Lyell. These events all inspired sombre reflections in Darwin’s letters. Nevertheless, all the Darwin children were thriving. When illness made work impossible, Darwin and Hooker read a number of novels, and discussed them in their letters.