quintessential D-ness

Absolute pitch is as much a quandary for philosophers as it is for neuropsychologists. Is there really such a thing as F-sharpness? The analogy to color, and to color blindness, doesn't really make sense. Whatever the color red may "be," it corresponds to a particular range of wavelengths of light, just as an adjacent range corresponds to the color orange. The brain finds distinct color experiences within the two ranges. If we were to begin referring to the spectrum differently, so that what we called "red" extended from the middle of normal red to the middle of normal orange, our brains would not obligingly regard the reddish orange at the center of the new range as a distinct color. But we do just this with absolute pitch. As we've seen, the tuning of instruments has shifted markedly over centuries. Mozart's D is not our D. Yet somehow the absolute-pitcher hears quintessential D-ness in today's D just as Mozart did in the D of his time.

-- Robert Jourdain Music, the Brain, and Ecstasy