The Art of Noises, Luigi Russolo
In antiquity, life was nothing but silence. Noise was not really born before the 19th century, with the advent of machinery. Today noise reigns supreme over human sensibility. For several centuries, life went on silently, or mutedly. The loudest noises were neither intense, nor prolonged nor varied. In fact, nature is normally silent, except for storms, hurricanes, avalanches, cascades and some exceptional telluric movements. This is why man was thoroughly amazed by the first sounds he obtained out of a hole in reeds or a stretched string. Primitive people attributed to sound a divine origin. It became surrounded with religious respect, and reserved for the priests, who thereby enriched their rites with a new mystery. Thus was developed the conception of sound as something apart, different from and independent of life. The result of this was music, a fantastic world superimposed upon reality, an inviolable and sacred world.
This, Vorspiel, is the cascade of the Rhine. The beginning of Das Rheingold is certainly ‘something apart, different and independent of life.’ (even though this is exactly the kind of music Russolo was writing against)