The first notes on the clarinet are simply a rising scale, but it is split down the middle: the first half belongs to C-sharp major, the second half to G major. This is an unsettling opening, for several reasons. First, the notes C-sharp and G are separated by the interval known as the tritone, one half-step narrower than the perfect fifth. (Leonard Bernstein’s “Maria” opens with a tritone resolving to a fifth.) This interval has long caused uneasy vibrations in human ears; scholars called it diabolus in musica, the musical devil.
