Not only the piano music, but also the relatively unusual fact that Stravinsky composes at the piano, should concern us. It is noteworthy too that although Stravinsky's piano output is not very large, many of his orchestral works contain important concertante piano parts. That Petrushka and the Symphony in Three Movements were originally conceived as compositions for piano and orchestra, and then altered to their present form, perhaps represents a realisation on his part, prophetic at the time when Petrushka was composed, that the role of the piano as a solo instrument with orchestra could not remain in the same relationship to the orchestra, as protagonist, as had been the case in the nineteenth century.