What results [from the compositional system of Boulez's Structures] can only be described as composition by numerology. The possiblities are endless; a computer could be programmed to put down notes according to this prescription and in a very short time could turn out enough music to require years for its performance. By using different numerical rules -- using a knight's move, for example, rather than a bishop's move along the diagonals — music for centuries to come could be produced.
John Backus, "Die Reihe — A Scientific Evaluation", Perspectives of New Music I/I (Fall 1962): 170.
A composer's awareness of the plurality of functions of his own tools forms the basis for his responsibility just as, in everyday life, every man's responsibility begins with the recognition of the multiplicity of human races, conditions, needs, and ideals. I would go as far as to say (as my anger comes back) that any attempt to codify musical reality into a kind of imitation grammar (I refer mainly to the efforts associated with the Twelve-Tone System) is a brand of fetishism which shares with Fascism and racism the tendency to reduce live processes to immobile, labeled objects, the tendency to deal with formalities rather than substance. Claude Lévi-Strauss describes (though to illustrate a different point) a captain at sea, his ship reduced to a frail raft without sails, who, by enforcing a meticulous protocol on his crew, is able to distract them from nostalgia for a safe harbor and from the desire for a destination.
Luciano Berio, in "The Composer on His Work : Meditation on a Twelve-Tone Horse", in Classic Essays on Twentieth-Century Music : A Continuing Symposium (1996) edited by Richard Kostelanetz and Joseph Darby, ISBN 0-02-864581-2, p. 169
Alas, this industrialized twelve-tone horse, dull on the outside and empty inside, constantly being perfected and dragged to a new Troy in shadow of an ideological war long since fought and won by responsible minds like Schoenberg, with neither systems nor scholarship for armor!
Luciano Berio, in "The Composer on His Work : Meditation on a Twelve-Tone Horse", in Classic Essays on Twentieth-Century Music : A Continuing Symposium (1996) edited by Richard Kostelanetz and Joseph Darby