 It was in February of 1867 that Darwin decided to remove material from his massive manuscript of the Variation of Plants and Animals Under Domestication and create a “very small volume, ‘an essay on the origin of mankind’” (Darwin to Hooker, 8 February 1867 and CD to Turner, 11 February 1867, Burkhardt et al. 2006 15: 74, 80). At this time he also sent to several correspondents a questionnaire asking for information on human emotional expression. This expanded into a major enterprise in which he became deeply engaged with the issue of the implications of his theory for ethics, writing to Asa Gray that “the difficulties of the Moral sense has [sic] caused me much labor” (CD to Gray, 15 March 1870, Burkhardt et al. 2010 18: 68). This was expanded into a two volume work by the time it was sent to the printer in June of 1870. By this date he had also pulled out a separate section from the Variation manuscript that was to become the Expression of the Emotions in Man and the Animals,published in 1872.