The Tristan Chord
Richard Wagner’s opera, Tristan und Isolde, really took connecting music and drama to a whole new level. The opera’s story comes from Celtic legend and centers around a knight, Tristan, and a princess, Isolde, who fall madly in love despite the fact that Isolde is already promised to another man. It’s a classic story of unrequited love that is said to have influenced countless other legends including the affair between Lancelot and Guinevere in the King Arthur tales.
Wagner’s score for the opera heavily exploits the feeling of longing that Tristan and Isolde feel for one another. Since their longing and desire go unfulfilled until they both die at the end of the opera, so does the music. One chord in particular, the Tristan Chord, completely embodies this idea of unfulfilled desire. Check out how the Tristan Chord is first introduced in the prelude:
It’s a chord that seems to appear out of nowhere, it’s not really natural to the key of the music and it doesn’t resolve the way we expect it to. Western music is built on the idea of tension and resolution. What we call dominant harmonies create this tension and resolve into tonic harmonies. Tonic harmonies give us a sense of closure and fulfillment. Our ears are used to hearing these resolutions at the end of basically every melody.
In Tristan und Isolde, Wagner makes us wait until the very end of the whole opera (which is about four and a half hours) to hear a resolution of the Tristan chord. The effect is unnerving. The music mirror’s Tristan’s heart as he longs for Isolde - it sounds like what being lovelorn feels like and it’s basically all based on this one chord, the Tristan Chord.
The Tristan Chord did much more than just connect the music and drama in this one Wagner opera. It's one of the first moments in music history where we see a composer using a particular chord because of the way it sounds instead of the chord he should use in order to follow the conventional rules of tonal music. Wagner used the Tristan Chord because it sounds like the feeling of being lovelorn. This gave the way for composer's like Claude Debussy to continue to break the rules. In Nuages from the Nocturnes, Debussy moved between very ethereal sounding chords without any regard for their "correct" resolution. The result sounds like clouds floating aimlessly in the sky (hint: nuage is French for cloud).
The impact of the Tristan Chord can still be felt today. For one, we can see the this same of idea of connecting the drama and music in the film scores of John Williams. But, perhaps more importantly, the Tristan Chord marks a shift in music history away from the traditional rules of tonality. It opened the flood gates for more and more composers to experiment and challenge the traditions of harmony. In the next century, whole groups of composers abandoned these rules all together in favor of new rules, like Arnold Schoenberg's 12-tone system, or no rules at all (atonality) - but that's another story.
If you have a spare four and half hours and speak German, give the whole opera a listen! If not you can skip to the end to hear that final resolution as Isolde dies beside Tristan. The magic moment happens right at 14:11.