The Devil’s Interval – The Tritone is a focused study of one of the most powerful and intriguing intervals in Western music. Spanning exactly half an octave, the tritone has occupied a singular place in musical thought for centuries: feared in medieval theory, absorbed into the core of tonal harmony, and later embraced by composers, jazz musicians, rock artists, and film scorers as a source of instability, drama, color, and expressive force. This monograph traces that journey clearly and practically, showing how the tritone works acoustically, theoretically, historically, and musically.

What gives this study its distinctive value is its combination of historical sweep and compositional usefulness. It examines the tritone in dominant harmony, voice leading, cadence, jazz substitution, melodic writing, symmetry, and modern stylistic applications, while also surveying its presence across major eras and genres—from chant and Bach to Wagner, Bernstein, Black Sabbath, and film music. Written for students, composers, arrangers, performers, and curious listeners, it is both a clear reference and a creative guide. Its central insight is simple: no other interval in Western music has carried so much tension, ambiguity, symbolism, and transformative power.