Extracts from Letters to Henslow, taken from ten letters Charles Darwin wrote to John Stevens Henslow from South America during the second survey expedition of HMS Beagle, were read to the Cambridge Philosophical Society on 16 November 1835 by Henslow and Adam Sedgwick, followed on 18 November by geological notes from the letters which Sedgwick read to the Geological Society of London. On 1 December 1835 they were printed as a pamphlet for private distribution.

Charles Robert Darwin was an English naturalist, geologist and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended from a common ancestor is now generally accepted and considered a fundamental concept in science. In a joint publication with Alfred Russel Wallace, he introduced his scientific theory that this branching pattern of evolution resulted from a process he called natural selection, in which the struggle for existence has a similar effect to the artificial selection involved in selective breeding. Darwin has been described as one of the most influential figures in human history and was honoured by burial in Westminster Abbey.