SUMMARY
The end of the Second World War can be understood as an important aesthetic dividing point in the history of modern music. The unstable spiritual climate, imbued with dreadful recollections of the just finished war, pervaded with the fear of a vague future, together with lengthy isolation and the discontinuity of musical life, enabled and dictated the young generation of composers to a radical change of traditional musical »language«. They were influenced from Schönberg's twelve-tone technique, but they applied the central idea, the arrangement of all twelve semitones of an octave in one row, also on other parameters of sound (rhythmic values, dynamics, articulation). In 1951 Pierre Boulez wrote his composition Structures Ia for two pianos in which he realized the idea of homogeneous serial structure. The series for separate parameters of sound were arranged in tabular form, their distribution was however controlled with »super-series«, derived from the basic series. In the same year John Cage also organized the musical material for his composition Music of Changes in tabular form. He was actually the first who indicated the possibility of organizing the material for all parameters of sound in separate tabulated lists. Yet he did not select any »super-series« and instead of the distribution of organized musical material of rational systematics he chose assigned by the tossing of three coins. Thus, two compositions for which both composers selected very similar basic concepts led paradoxically to complete separation, so that Boulez and Cage are usually connected with two seemingly diametrical opposite streams of music after the Second World War: serial and aleatoric music. The analyses of the final acoustic realizations of both compositions give us however very similar results, which throws a new light on the efforts of both composers from the beginning of the '50s of the 20th century and gives them a special documentary value. In both cases, we hear a variety of mutual unconnected tones, spread over a wide tone-range, without distinct metrical impulse in a constant and contrasting change of dynamics. Therefore, the analysis should not be concentrated on the melody, harmony, regular rhythmical-metrical pulse, motivic-thematic work or classical formal construction; musical texture depends much more on the physical parameters of sound and their change (density, average volume and frequency, and number of musical events in a time unit). In this way, both compositions bear witness to a special state of music material and compositional technique after the Second World War and share the common desire for developing a new musical »language«.