Philosophy of Music
What we define as music is a mental content generated by the ears and the brain, responding to external vibrational stimuli. This stimuli cause the musical perception, but are substantially different from it. Being each individual unique, cerebrally and psychologically, each one has its own particular way to respond to the external stimuli, having thus a more or less different experience from the listening of a same music piece. It's not possible to express objective and absolute judgements about a tune, not existing a reference version of it; in a certain sense there are as many versions as there are listeners.
by Thomas Becker