The title 'Boum' comes from a novel by E.M. Forster,entitled A Passage to India, and is represented in themusic by an ominous tam-tam stroke. This is the firstsound we hear in the symphony. The 'boum' represents a mysterious echo experienced by characters inA Passage to India, on a visit to the Marabar Caves. Theecho comes to symbolize the mysteries of life and death,and is a starting point to a general theme of existentialism and human struggle that pervades the symphony.