‘your Book is one of the most attractive dishes in my Literary Banquet—’ (letter from John Murray, 6 November [1872])

Darwin opened his first notebook on expression, marked ‘Private’, in 1838, and kept another with detailed observations of his children from the birth of his first son, William, in 183g. He originally intended to include a chapter on human descent, which would have incorporated some of these observations, in Variation under domestication, but by the time Variation went to press in 1866, he had amassed too much material and held it back for separate publication. In 1867, while working on Descent, he drew up a series of questions about human expression which he circulated first as a handwritten list, and then, from late 1867 or early 1868, as a printed questionnaire (Correspondence vol. ig, Appendix VII; see also this volume, supplement). Descent was published in February 1871, but again Darwin had too much material, and by mid-1870 had decided to publish a separate ‘essay’ on the expression of emotion in both humans and animals (Correspondence vol. 18, letter to James Crichton-Browne, 8 June [1870]).

Darwin began writing Expression on 17 January 1871, and finished the first draft of the manuscript on 27 April. Work was suspended to allow him to concentrate on the sixth edition of Origin, but resumed immediately he finished correcting the proofs of that on 10 January 1872. A revised manuscript of Expression was sent to the printers in June; Darwin and his daughter, Henrietta Emma Litchfield, finished revising and correcting the proofs on 22 August, binding began in October, and it was published on 26 November 1872. In addition to a number of engravings, the volume contained seven plates with photographs reproduced using a new process of heliotyping. (Freeman 1977; Correspondence vol. 19, Appendix II; CD’s ‘Journal’ (Appendix II); see also the introduction to this volume.)