Part Four — Leaving Home
The surest way to learn what a habit does is to break it. Four departures from the tonic, and what each one reveals about the home it left.
If the tonic were a law of nature, music without one would be unintelligible, like sentences without grammar. If it were purely convention, abandoning it would cost nothing. The history of the last hundred and sixty years suggests neither extreme is right. Composers left home in several directions, and listeners followed some of them more willingly than others. Their routes are the final evidence in this essay.
Wagner: the home deferred
Richard Wagner's Tristan und Isolde, first performed in Munich in 1865, opens with a chord that analysts have argued over ever since. What matters for our purpose is less its label than its behaviour: it moves to a dominant-sounding sonority that does not resolve to the expected tonic. Throughout the opera, cadences are approached and evaded. The full resolution is withheld, by most accounts, until the final pages.
Wagner did not abolish the tonic. He weaponised the listener's expectation of it, exactly the mechanism Leonard Meyer would later describe. Four hours of longing depend on the audience knowing, in their bones, where home would be. Tristan is the strongest possible proof of how deeply tonality had been learned.
Debussy: the home blurred
Claude Debussy took a different road. In "Voiles", from the first book of his Préludes (1909–10), most of the piece uses the whole-tone scale, in which every step is the same size. With no semitones there is no leading tone, and without a leading tone the dominant's pull from Part Two cannot operate. A low B-flat recurs like a pedal and gives the piece an anchor, but it is a resting place more than a destination. Debussy kept a centre and removed the grammar of arrival.
Every departure from the tonic was written for listeners who knew exactly where home had been.Part Four
Schoenberg: the home refused
Arnold Schoenberg went furthest. The final movement of his Second String Quartet (1908), with its soprano singing that she feels "air from another planet", is often cited as the threshold of his atonal music, in which no pitch is meant to function as tonic. In the early 1920s he formalised the approach as the twelve-tone method, ordering all twelve chromatic notes into a row so that none would be favoured by repetition.
The method addresses precisely the statistical learning described in Part Three: if the tonic is partly the most frequent note, equalising frequency should erase it. To a considerable degree it works. Yet listeners still report momentary centres in twelve-tone music, drawn by register, duration and emphasis. The ear, it seems, keeps searching for home even when told there is none. That is not an argument against Schoenberg's music, much of which is extraordinary; it is evidence about the ear.
Modal jazz and the loop
Miles Davis's Kind of Blue (1959) offers a quieter alternative. In "So What", long stretches rest on a single Dorian mode with very few chord changes. There is a centre, but the dominant-to-tonic engine is mostly idle; home is established by duration, much as the tanpura does in Part One. The circle closes. Popular music since has often done something similar, building songs on repeating chord loops where listeners may genuinely disagree about which chord is home, and seem to enjoy the ambiguity.
Conclusion: home as an act
Across four parts, the argument has gathered its pieces. Acoustics gives certain intervals a natural stability. Harmony builds on that stability a grammar of departure and return. Experiments show that listeners absorb this grammar from exposure and apply it reliably. And the departures show that the habit is deep enough to be exploited, blurred and resisted, but never simply ignored.
Our considered view, then, is this: the tonic is not a property of a note, nor a mere convention, but an act of listening, a continuous, largely unconscious judgement about where the music belongs. Composers can guide that judgement or frustrate it. They cannot stop us making it.