From a review of Wagner and the Erotic Impulse by Laurence Dreyfus, published in the Chronicle of Higher Education (December 20):
No one has ever written about eroticism in Wagner’s music quite like this:
“In one long chapter, Dreyfus demonstrates (musical non-specialists may pause at the terminology but will get the gist) how, for example, Wagner summoned up intertwining bodies through melodic combinations and invertible counterpoint, suggested gender or bodily position through high and low instruments and their tessituras, and enacted sexual climaxes through tonal closure and percussive explosions.”
Wagner scholarship has never given it due credit.
“Dreyfus considers it too prudish, too removed even from the processes and emotions of music making. He writes: ‘What we mustn’t do is switch off our own erotic sensibilities when responding to art – a syndrome that, depressingly, appears far too often in academic discourse. As soon as we do so, we impoverish aesthetic experience and deprive ourselves of the blindingly obvious.’”
Eric Koch’s book, The Weimar Triangle, is available at Indigo-Chapters and in your local bookstore. 
When has not the erotic been lurking in the back (or foreground) of any successful aesthetic experience?