Steve Schwartz:

>Stravinsky didn't change because he wanted to be "progressive."
>Or at least that wasn't the main reason.  He changed because he
>felt he had worn out the style he was using. He felt written out.

I think this is more true of Copland, who said he needed some "new notes."
But Stravinsky reportedly explained his adoption of serialism by saying
something like "I have to keep up my reputation as an innovative young
composer." This may have been his way of saying, "Get off my back," but
his choice of words is significantly different from Copland's.  I'd always
understood that it was Robert Kraft, whom Stravinsky took on as secretary
after Schoenberg's death, who was at least the catalyst for Stravinsky's
stylistic shift, but I suppose there must have been some predisposition in
that direction to pave the path.

Jim Tobin