The development of music in Western civilization shows a constant inter action between the structural and the sonoro.us-expressive elements in musical composition. The emphasis on sonority, on harmony, contrasts with the em phasis on counterpoint, of which the construction is the extreme development. Canonic technique in 15th century music, with its manifold structural possibilities, is the ultimate development of the constructional principle in early polyphony. But within this frame-work the harmonie element gains importance and gradually becomes the center of gravity; tonality and text...