Copland came to the conclusion that composing along serial lines was "nothing more than an angle of vision. Like fugal treatment, it is a stimulus that enlivens musical thinking, especially when applied to a series of tones that lend themselves to that treatment." He began his first serial work, the "Piano Fantasy", in 1951 to fulfill a commission from the young virtuoso pianist William Kapell. The piece became one of his most challenging works, over which he labored until 1957. During the work's development, in 1953, Kapell died in an aircraft crash. Critics lauded the "Fantasy" when it was finally premiered, calling the piece "an outstanding addition to his own oeuvre and to contemporary piano literature" and "a tremendous achievement". Jay Rosenfield stated: "This is a new Copland to us, an artist advancing with strength and not building on the past alone."