The Austrian composer and conductor Gustav Mahler (1860-1911) introduced innovations which had a profound influence on the Viennese composers of the next generation and initiated significant trends in operatic production that set a new standard.

Gustav Mahler once said: "Composing a symphony means, to me, building a new world with every available technical means. The ever-new and changing content determines its own form." This free concept of symphonic form included such innovations as "progressive tonality," that is, beginning a symphony in one key and ending it in a quite different one. Such practices were often misunderstood and rejected by Mahler's contemporaries. However, he became resigned to this, for, as he liked to say, "My time will yet come." His prophecy proved to be right, for in the second half of the 20th century he became one of the most popular symphonic composers.

Mahler can be seen as an...