Our music has sprung from the patient, incessant, and progressive penetration into the law of resonance, that is to say, from the successive exploitation of the octave , the fifth and the fourth (ninth to twelfth century), the third (thirteenth to sixteenth century), the seventh (seventeenth and eighteenth century), the major ninth , the augmented fifth , and the perfect eleventh (nineteenth and twentieth centuries) . . . . this evolution . . . . constitutes, at the same time, the only true justification of the musical art.

http://www.moviequotedb.com/movies/songwriter/quote_77708.html