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. When requested to provide words to celebrate what would have been the naturalist and traveller Alexander von Humboldt's 105th birthday, Darwin obliged with a reflection on his debt to Humboldt, whom he had greatly admired in his youth: ‘I have always looked on him as one of the greatest men the world has ever produced. He gave a wonderful impetus to science by showing what could be done by observation during prolonged intervals' (letter to D. T. Gardner, [c. 27 August 1874]). The death of a Cambridge friend, Albert Way, caused Darwin's cousin, William Darwin Fox, to reminiscence about their university days together, and the long-abandoned pleasures of shooting and collecting beetles (letter from W. D. Fox, 8 May [1874]). Such reminiscences led Darwin to the self-assessment, ‘as for one's body growing old there is no help for it, & I feel as old as Methusalem; but not much in mind except that I think one takes everything more quietly, as not signifying so much. And … one looks backwards much more than forwards' (letter to W. D. Fox, 11 May [1874]).

The year started for Darwin with a week's visit to London, staying at his brother Erasmus's house. He requested a visit from his doctor, Andrew Clark, whom he had been consulting since August 1873. Darwin had originally thought that Clark's dietary treatment would ‘do wonders’, but as he confessed to his old Beagle shipmate Bartholomew James Sulivan, ‘it was an illusory hope.— I feel very old & helpless’ (letter to B. J. Sulivan, 6 January [1874]). Darwin mentioned his poor health so frequently in correspondence that Ernst Haeckel inferred that he was well from his silence on the matter (letter from Ernst Haeckel, 26 October 1874).