||In The Firebird, Stravinsky followed the Russian convention of sharply contrasting the music of the human characters against that of the supernatural characters. Most theorists posit that the human characters are portrayed with principally diatonic music, and the supernatural with principally chromatic music. In the case of the supernatural, the tritone, as personification of the two magical characters, Kastchei and the Firebird, is the basis for all of the music Stravinsky applies to them. He makes extensive use of it as bookends to the pitch sets of their two leitmotifs, both drawn from the first six notes of the opening ostinato. The ubiquitous tritone is of prime importance in the building of intervallic, motivic, and harmonic elements in the piece and helps to provide unity in the work as a whole. My greatest contribution in analyzing the music of The Firebird relates principally to the music representing the Princesses, captive humans under the supernatural control of Kastchei. In this dissertation, I will demonstrate that this music, commonly believed to be primarily folk or diatonic, and therefore given less importance by theorists, in actuality, is in large part constructed from the same source materials that spawned the supernatural music of the Firebird and Kastchei. Undoubtedly, the Princesses' music has frequent harmonic and motivic hints in the foreground and background of the chromatic leitmotifs of the principal supernatural characters. In addition, musical motifs in the "Princesses" sections are at times constructed by giving the pitch sets of the supernatural characters a more "diatonic" quality, extending or contracting their outer interval of a tritone by a semitone, to form perfect fourths or fifths. There is evidence that, for Stravinsky, this was part of the reasoning governing his motivic, intervallic, and harmonic choices. The perfect fifth, certainly, was seen as representative of the human element of the work, while the tritone was seen as representative of the supernatural element. The combination of the two elements is what makes the composition of Stravinsky's Firebird truly masterful.