Tonic

What it means

The tonic is the first degree of a key and the triad built upon it, in function theory T (I). It is the centre of the key, the sonority in which the music rests and to which it returns. All other functions are related to it: the dominant leads toward it, the subdominant leads away from it.

Musical use

The status of the tonic does not arise on its own but is established through cadences. A sonority becomes the tonic by the dominant leading to it; only the progression D–T confirms the centre. This is why the same triad can be the tonic in one piece and the dominant in another — its function results from the context, not from the sonority itself.

At the beginning and end of a piece, tonal music as a rule stands on the tonic; the close usually appears as a perfect authentic cadence with the root in the bass and in the top voice. Within a movement the centre can change, when the music modulates; the new key then has its own tonic.

The tonic has representatives that share two notes with it: the tonic's relative on the sixth degree and the tonic's counter-chord on the third. The tonic's relative replaces the tonic in the deceptive cadence.

The tonic is to be distinguished from the finalis of modal music: the finalis is the closing and reference note of a melody, without there having to be a functional pull leading toward it; the tonic is the centre of a system of relations.

The tonic is the starting and goal point of music in major-minor tonality. Its representatives are the tonic's relative and the tonic's counter-chord, which offer repose without a complete close.

Performance practice

Give the tonic repose at the close, not force — it works through arrival, not through loudness. As you work on a piece, watch where the tonic is confirmed and where the piece leaves it. And intonate the final chord carefully; every deviation is especially audible in it.