In 1921, insurance executive Charles Ives sent out copies of a piano sonata to two hundred strangers. Laden with dissonant chords, complex rhythm, and a seemingly chaotic structure, the so-called Concord Sonata confounded the recipients, as did the accompanying book, Essays before a Sonata. Kyle Gann merges exhaustive research with his own experience as a composer to reveal the Concord Sonata and the essays in full. Diffracting...