 Herbert Spencer (1820–1903) defended an explanation of the origin of music distinct from Darwin’s. Spencer holds as a general physiological principle that any emotion produces movement. When movement involves the vocal tract, emotions result in vocalizations. Music derives from an exaggeration of the usual features of vocal emotional expression. Thus, “vocal music, and by consequence all music, is an idealization of the natural language of passion” (Spencer 1857 [2015: 29]). This view of music’s origin locates its expressive value in the melodic element, rather than in harmony, as expressive vocalizations do not produce more than one sound at once. However, Spencer emphasizes that his explanation of music’s origin is not to be taken as a general theory of music’s value, and that elements of music that are not amenable to its original function (notably harmony) remain entirely legitimate (Spencer 1890: 466–467). Factual hypotheses regarding music’s origin are thus separated from aesthetic norms. This is a relevant methodological difference between Spencer’s hypothesis about the origin of music and previous ones, most notably Rousseau’s (see the entry  history of western philosophy of music: from antiquity to 1800, section 3.5).