James Luckett has recognised the subject of the grafitti near Bruntsfield Links (Breaking news 9.10.10).
It was certainly based on a photograph of the 'German philosopher and all-round fun-guy' Friedrich Nietzsche (1844–1900).
'Nietzsche,' Mr Luckett continues, 'famously stated that "Art is not merely an imitation of the reality of nature, but in truth a metaphysical supplement to the reality of nature, placed alongside thereof for its conquest"'.
Erm ... quite. Think I'll go and buy a pick-up.
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Update
On 16.8.11 the source for this work's caption was identified as a song by Neil Young, Out on the Weekend.