Lecture 5 picks up at the early twentieth century with an oncoming crisis in Western Music. As these lectures have traced the gradual increase and oversaturation of ambiguity, Bernstein now designates a point in history that took ambiguity too far. Twelve-tone music emerges as one potential solution to the crisis, but Bernstein considers this idiom so ambiguous that it destroys the all-important balance between clarity and ambiguity.