What is... Tonality?

Tonality is, in simple terms, the key in which a piece of music is written, or a word to denote music written using conventional keys and harmony.

Mention tonality, keys and key-relations to non-musicians and chances are what you’ll get in response is a wan, distracted kind of look. It can all seem so airy, or just dry. Themes are easy enough to identify, same with instrumental colours, but keys? But I’d argue is that, far from abstract, tonality is one of the most visceral forces in Western music, and not just classical music.

To grasp it in terms that make concrete physical sense, try thinking of a traditional Anglican hymn – say, ‘O God, our help in ages past’. Think of the first two phrases: ‘O God, our help in ages past, Our hope for years to come’. The chord on the final ‘come’ feels relatively conclusive – but at the same time not quite conclusive enough.

It’s a different chord from the one on ‘God’, and on ‘past’, and as such it feels as though stopping here can only be temporary. Then comes ‘Our shelter from the stormy blast’, and the chord accompanying ‘blast’ feels remoter still. But then comes the pay-off: ‘And our eternal home’.

The chord on the final ‘home’ really does feel as thought we’ve come ‘home’: there’s a feeling of having landed securely, at last, on solid ground. Add a conventional ‘Amen’ and the point becomes even clearer. Stop on the ‘A-’ and the journey isn’t complete: add ‘-men’ and we have again reached terra firma; ‘-men’ brings us back to the same chord as ‘home’ and ‘God’, and it’s clear that this now functions as a musical centre of gravity.

Our stomach muscles relax pleasurably when we return to it. The journey away from home can be pleasurable too, but the sense of resolution the coming back brings is fundamental – this is what the journey has been for.

Expand that onto a larger scale and you have the kind of tonal argument you get in a Beethoven symphony. The first theme is in the ‘God’ or ‘home’ tonal territory; the second theme is introduced in a different key, after a dramatic key-change: ‘Our hope for years to come’.

The development takes us through less stable, more stressful regions: ‘Our shelter from the stormy blast’. But then comes the recapitulation, with now both first and second themes in the ‘home’/‘God’, key.

The point is that this isn’t just a cerebral process; it’s physical, emotional too. If you’ve been moved by the drama of a Beethoven symphony, then you’ve certainly felt it. What I hope this has shown is that, from that to understanding tonality isn’t such a huge step.

This article was first published in the May 2016 issue of BBC Music Magazine