The tritone splits the octave in half, forming a harmonic ratio of √2—an irrational number that repeats into infinity without resolving. Although this was unknown in medieval Europe, its sonic tension was deeply felt, profound enough to earn the name diabolus in musica. It’s as if the dissonance of the tritone posed a direct challenge to the religious craving for perfection and symmetry of the times. In a world built on pure fifths and major tonality, the tritone was an intruder—a sound that threatened a supposedly orderly cosmos. Humans have always feared what we can’t explain, yet even then, listeners intuited the anomaly without knowing that Mother Nature was at the chalkboard, sketching equations in the language of vibration. Unable to read her script, we called the sound unholy—failing to see it for what it was: a whisper of infinity in the fabric of harmony.