what was to be his last ballet for Diaghilev, The Prodigal Son. When first staged in Paris on 21 May 1929, choreographed by George Balanchine with Serge Lifar in the title role, the audience and critics were particularly struck by the final scene in which the prodigal son drags himself across the stage on his knees to be welcomed by his father. Diaghilev had recognised that in the music to the scene, Prokofiev had "never been more clear, more simple, more melodious, and more tender". Only months later, Diaghilev died. That summer, Prokofiev completed the Divertimento, Op. 43 (which he had started in 1925) and revised his Sinfonietta, Op. 5/48, a work started in his days at the Conservatory. In October of that year, he had a car crash while driving his family back to Paris from their holiday: as the car turned over, Prokofiev pulled some muscles on his left hand. Prokofiev was therefore unable to perform in Moscow during his tour shortly after the accident, but he was able to enjoy watching performances of his music from the audience. Prokofiev also attended the Bolshoi Theatre's "audition" of his ballet Le pas d'acier, and was interrogated by members of the Russian Association of Proletarian Musicians (RAPM) about the work: he was asked whether the factory portrayed "a capitalist factory, where the worker is a slave, or a Soviet factory, where the worker is the master? If it is a Soviet factory, when and where did Prokofiev examine it, since from 1918 to the present he has been living abroad and came here for the first time in 1927 for two weeks [sic]?" Prokofiev replied, "That concerns politics, not music, and therefore I won't answer." The RAPM condemned the ballet as a "flat and vulgar anti-Soviet anecdote, a counter-revolutionary composition bordering on Fascism". The Bolshoi had no option but to reject the ballet. With his left hand healed, Prokofiev toured the United States successfully at the start of 1930, propped up by his recent European success. That year, Prokofiev began his first non-Diaghilev ballet On the Dnieper, Op. 51, a work commissioned by Serge Lifar, who had been appointed maitre de ballet at the Paris Opéra. In 1931 and 1932, he completed his fourth and fifth piano concertos. The following year saw the completion of the Symphonic Song, Op. 57, which Prokofiev's friend Myaskovsky—thinking of its potential audience in the