Claudio Monteverdi's historical position in music has been compared to that of Shakespeare in literature: almost exact contemporaries, each worked from traditional beginnings to transform nearly every genre he attempted. In this book, Massimo Ossi delves into the most significant aspect of Monteverdi's career: the development, during the first years of the 17th century, of a new compositional style he called the "seconda prattica" or "second manner". Challenged in print for the unconventional aspects of his music, Monteverdi found himself at the centre of a debate between defenders of Renaissance principles and the newest musical currents of the time. The principles of the "seconda prattica", Ossi argues in this sophisticated analysis of Monteverdi's writings, music and texts, were in fact much more significant to the course of Monteverdi's career than previously thought by modern scholars - not only did they affect Monteverdi's output for the rest of his life, but as his works became widely known they influenced subsequent composers more than is often imagined. Ossi "divines the oracle" of Monteverdi's ambiguous theoretical concepts in a clear way and in terms of pure music; his book should enhance our understanding of Monteverdi as one of the most significant figures in western music history.