Which classical music composer wrote The Song of the Earth?

Das Lied von der Erde ("The Song of the Earth") is a composition for two voices and orchestra by the Austrian composer Gustav Mahler between 1908 and 1909. Described as a symphony when published, it comprises six songs for two singers who take turns singing the songs. Mahler composed this work following the most painful period in his life, and the songs address themes such as those of living, parting and salvation. On the centenary of Mahler's birth, the composer, conductor, and known Mahler conductor Leonard Bernstein described Das Lied von der Erde as Mahler's "Greatest symphony".