[No.] 15 [Description] The prelude is a brusque waltz typical of Shostakovich. The opening theme resembles "We Wish You a Merry Christmas". The date of the composition (20 December) may explain this. The vivace fugue is a tour de force of chromatic and atonal writing. The subject contains 11 of the 12 semitones available. [Key] 
D-flat major