The "Tristan Chord" from Wagner's opera "Tristan und Isolde" defied traditional harmony, setting a cornerstone for modern music's evolution. This chord's ambiguity and dissonance resolved in an unprecedented way, challenging conventions and paving the way for 20th-century musical exploration. Wagner’s harmonic innovation led directly to the atonal music of Schoenberg, shaping the fabric of classical and modern music alike. Share your own favorite groundbreaking musical moment or discovery!