Variation as a musical form, however, is something special. Essentially you take a self-sufficient musical theme and repeat it, but with significant alterations, so that its character and meaning are transformed.
In Bach’s ingenious Goldberg Variations the composer brings back the theme, as heard at the beginning, at the very end – partly to round off the experience; partly to show how far we’ve travelled.
Near the end of Elgar’s Enigma Variations the ‘original’ theme returns majestically, but now in the major key (it was originally minor) and in three-time instead of the original four. The effect is quite different.
Elgar’s theme has gone on a journey, and emerged as something new – transformed by the life experience represented in the course of the work.
There’s another important distinction between Bach’s variations and Elgar’s. In Elgar’s Enigma the process is mostly what you might call ‘melodic’ variation.
The original theme is audibly present in each one of the 14 variations, however much Elgar may decorate it, extend it here or contract it there. The effect is like a series of portraits of the same person, but in different costumes and settings, engaged in different kinds of activity.
In the Bach however, it is not so much the tune as the bass-line – along with harmonies built upon it – that remains constant. However long or short the variations, each one is clearly based on the same harmonic template, the proportions more or less the same – let’s call this ‘harmonic’ variations.
In sets of variations from the Classical era, the ‘harmonic’ type prevails. Often the tune itself seems to disappear, but the sense of the same basic pattern repeating, cyclically, underpins everything.
Often the note values increase towards the climax: at first quavers, then triplets, then semiquavers, etc… but that circular, meditative pattern goes on working in the background.
The second movement of Beethoven’s Piano Sonata, Op. 111, is a classic example. After the volatile, unpredictable drama of the first movement, the second, in contrast, offers contemplation, and finally peaceful resolution.
Another reminder that, in great music, form and emotional expression are inseparable.
This article was first published in the September 2012 issue of BBC Music Magazine