3 by Walter Piston is a chamber-music work composed in 1947.
Piston's third string quartet was commissioned by Harvard University and first performed by the Walden String Quartet on May 1, 1947.
The central Lento movement is a calm theme and variations in C minor.
[2] However, the first movement actually begins in A♭ major/minor, only gradually settling into F minor at the end, and the variation movement spends a lot of its time in the parallel major (the dominant of F minor).
However, Piston's characteristic flexibility of tonality and thickly chromatic harmony makes it simplest to omit key signatures.