“The over-publicized bit about expression (or non-expression) was simply a way of saying that music is supra-personal and super-real and as such beyond verbal meanings and verbal descriptions. It was aimed against the notion that a piece of music is in reality a transcendental idea ‘expressed in terms of’ music, with the reductio ad absurdum implication that exact sets of correlatives must exist between a composer’s feelings and his notation. It was offhand and annoyingly incomplete, but even the stupider critics could have seen that it did not deny musical expressivity, but only the validity of a type of verbal statement about musical expressivity. I stand by the remark, incidentally, though today I would put it the other way around: music expresses itself.”
Igor Stravinsky and Robert Craft, Expositions and Developments