Shostakovich's first Piano Sonata dates from the fall of 1926, only three years after the first piano trio, but it lives in an entirely different world. The May 1926 premiere of his First Symphony, a decidedly modernist work, had made the 19-year-old composer famous, and he explored new directions with great confidence despite the occasional consternation of his professors at the Leningrad Conservatory. The first piano sonata may be the most aggressively modern of Shostakovich's early works. The thematic elements sound atonal, but beneath all the muscular running chromaticism is a persistent tonal center in C. The one-movement sonata changes tempo a dozen times, but to the listener it boils down to a fast section, a slow section, and a fast section. The slow part creates more tension than repose, and the sonata as a whole conveys a feeling of constant and relentless motion. Shostakovich's former piano teacher called it a "sonata for metronome accompanied by the piano." Unlike the trio, it remained a favorite of Shostakovich for years: he played it often in his concerts, perhaps because he thought it a perfect vehicle for his brand of virtuosity.