the sole ensemble to interpret his works for many years, still remains active with many of its original members. After Drumming, Reich moved on from the "phase shifting" technique that he had pioneered, and began writing more elaborate pieces. He investigated other musical processes such as augmentation (the temporal lengthening of phrases and melodic fragments). It was during this period that he wrote works such as Music for Mallet Instruments, Voices and Organ (1973) and Six Pianos (1973). In 1974, Reich began writing Music for 18 Musicians. This piece involved many new ideas, although it also hearkened back to earlier pieces. It is based on a cycle of eleven chords introduced at the beginning (called "Pulses"), followed by a small section of music based on each chord ("Sections I-XI"), and finally a return to the original cycle ("Pulses"). This was Reich's first attempt at writing for larger ensembles. The increased number of performers resulted in more scope for psychoacoustic effects, which fascinated Reich, and he noted that he would like to "explore this idea further". Reich remarked that this one work contained more harmonic movement in the first five minutes than any other work he had written. Steve Reich and Musicians made the premier recording of this work on ECM Records. Reich explored these ideas further in his frequently recorded pieces Music for a Large Ensemble (1978) and Octet (1979). In these two works, Reich experimented with "the human breath as the measure of musical duration ... the chords played by the trumpets are written to take one comfortable breath to perform". Human voices are part of the musical palette in Music for a Large Ensemble but the wordless vocal parts simply form part of the texture (as they do in Drumming). With Octet and his first orchestral piece Variations for Winds, Strings and Keyboards (also 1979), Reich's music showed the influence of Biblical cantillation, which he had studied in Israel since the summer of 1977. After this, the human voice singing a text would play an increasingly important role in Reich's music. In 1974 Reich published the book Writings About Music, containing essays on his philosophy, aesthetics, and musical projects written between 1963 and 1974. An updated and much more extensive collection, Writings On Music (1965–2000), was published in 2002. 1980s Reich's work took on a darker character in the 1980s with the introduction of historical themes as well