There are few opportunities these days to hear live performances of the deeply felt, sonorously shaped music of the New England composer Walter Piston. His colleague Aaron Copland called Piston “one of the most expert craftsmen American music can boast,” which has become a standard assessment. It has also boxed him in. While intended as a compliment, this appraisal suggests Piston to be something of a technocrat, a musician of the mind rather than the heart. This impression is far from the case.