Book excerpt: The six string quartets dedicated to his friend Joseph Haydn represent a turning point in Mozart's compositional development. In addition to providing a full synopsis of each quartet this book examines the music in relation to Mozart's earlier quartets, considers the genesis of the six 'Haydn' quartets through close examination of the autograph revisions and looks at contemporary eighteenth-century analytical models. John Irving also charts the reception of the quartets, drawing upon a broad range of sources: Mozart's letters and diary entries, early newspaper reports, harmony/compositional textbooks, contemporary criticism and early biographies.