The Expression of the Emotions in Man and Animals typically accompanies blushing. A German translation of "The Expression" appeared in 1872; Dutch and French versions followed in 1873 and 1874. A second edition of the book, with only minor alterations, was published in 1890. Before Darwin, human emotional life had posed problems to the western philosophical categories of "mind" and "body". Darwin's interest can be traced to his time as a medical student and the 1824 reprint of Sir Charles Bell's "Anatomy and Philosophy of Expression" which argued for a spiritual dimension to the subject. In contrast, Darwin's biological approach links mental states to the coordination of movement, and
The Expression of the Emotions in Man and Animals with engravings of the Darwin family's domestic pets by the zoological illustrator T. W. Wood as well as work by the artists Briton Rivière, Joseph Wolf and A.D. May. It also included portraits by the Swedish photographer Oscar Rejlander (1813–1875), anatomical diagrams by Sir Charles Bell (1774–1842) and Friedrich Henle (1809–1885), as well as illustrational quotations from the "Mécanisme de la physionomie humaine" (1862) by the French neurologist Duchenne de Boulogne (1806–1875). As a result of his domestic psychology experiments, Darwin reduced the number of commonly observed emotions from Duchenne's calculation of more than sixty facial expressions, to just six