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- declamation are the determining factors
in this process. After a balance between these two principles of musical
composition had been achieved in 16th century classical polyphony, the
emphasis shifted to harmonie and subjective expressiveness until, at the
beginning of the 20th century, harmony and sonority disintegrated and
yielded before the construc- tional principle. In twelve-tone and serial
composition the tendency towards construction and objectivity is so
strong, that musical form is often determined by mathe- matical
structures. In electronic music such structures are adopted to deter-
mine the nature of the sonorities themselves, and the structural
principle of the tone-row is applied to the structure of sound in its
component harmonics. Thus new sonorities are created, which are freed
from the limitations of traditional musical sound, but which adhere to
the same structural principles as serial composition.