Of all his symphonies, Mahler gave the Fourth, his favorite and problem child, his most particular attention. “The Heavenly Life,” a humoresque composed in 1892 for soprano and piano, which he already wanted to use in the final movement of the Third Symphony under the title “What the Child Tells Me,” ultimately became the nucleus and final movement of the Fourth. Even after publication in 1901, Mahler kept repeatedly refining the orchestration. His maxim “not without my retouching” led to a whol...