A Popular History of the Art of Music From the Earliest Times Until the Present
CHAPTER V--THE TRANSFORMATION AND ITS CAUSES 81-86
General view of the transformation to modern music--causes co-operating--difference between ancient and modern music--harmony and tonality--consonance and dissonance--three steps in the development of harmonic perceptions--when were these steps taken?--tonality defined--growth of tonal perception--unconscious perception of implied or associated tones.