There is a double metaphorical link established between language and object when music is interpreted in sexual terms. In the first instance, the dualism between 'male' and 'female' principles is projected onto specific compositions or specific elements of these (a famous example is provided by A. B. Marx and his description of the thematic dualism of the played form); in the second, the traits of either gender are attributed to music as a whole: as exemplified by Wagner's claim in "Oper und Drama" that music is "per se" a woman (an example of 'absolute sexual metaphor'). This essay examines this Wagnerian metaphor by tracing some of its likely sources (Humboldt, Körner, Schlegel) and studying its ambiguities. The idea expressed in the 'absolute sexual metaphor' actually contradicts the theory - enounced by Wagner in the same years - according to which the origins of instrumental music must be searched for in dance. As a stylisation of dance gestures, music has thus, implicitly, both masculine and feminine traits. A comparison between Wagner's position and that of a contrary nature expressed in the twentieth century by Dorothy Richardson in the novel "Pilgrimage" in which the theses of contemporary feminist musicology are anticipated, facilitates reflection upon the risks of metaphoric simplifications in the absence of metacommunicative theories.