This lecture, called “The 20th Century Crisis,” is part of the lecture series The Unanswered Question, which Bernstein delivered in the Fall of 1973 as the Charles Eliot Norton Professor of Poetry, with poetry having as broad a definition as possible.
As the website Leonard Bernstein at 100 writes: “The fifth lecture (‘The Twentieth Century Crisis’) outlined the movement toward atonality and the crisis provoked by this crucial change in our musical language. Charles Ives’ “The Unanswered Question,” one of the primary musical examples, became Bernstein’s title for the entire series of lectures.”
It is noteworthy that Bernstein, more than anyone else in America, made the work of Gustav Mahler [1860–1911] better known to the general public, with good reason, since Bernstein considers Mahler a prophet of anguish and death, whose last symphony foretells the message of future despair—too dreadful to hear in his time and, for that matter, for the next 50 years. Bernstein calls the 20th century “the age of death; the end of faith.”
Mahler with his sensitive spirit felt this intently and with great urgency. All this, who want to listen intently, is found in Mahler’s last symphony. Yet, despite the tortured and terrifying music, interspersed with prayer and submission, we come out of it with renewed understanding. The full lecture on video can be found [here]. For more on the subject, go [here] and [here] and [here] and [here].