From a review of Leonard Bernstein’s 1973 Norton lectures at Harvard:
The truly emblematic twentieth-century composer is Mahler, whose attempts to relinquish tonality are reluctant and incomplete, and whose nostalgia for past practice is overt and tragic. Mahler’s Ninth Symphony, his “last will and testament,” shows “that ours is the century of death, and Mahler is its musical prophet.” That is the “real reason” Mahler’s music suffered posthumous neglect–it was, Bernstein says, “telling something too dreadful to hear.” The Ninth Symphony embodies three kinds of death–Mahler’s own, which he knew was imminent; the death of tonality, “which for him meant the death of music itself”; and “the death of society, of our Faustian culture.” And yet this music, like all great art, paradoxically reanimates us.