Theme and variations

In music, variation is a formal technique where material is repeated in an altered form. The changes may involve melody, rhythm, harmony, counterpoint, timbre, orchestration or any combination of these.

Mozart’s Twelve Variations on "Ah vous dirai-je, Maman"(1785),known in the English-speaking world as “Twinkle, twinkle, little star” exemplifies a number of common variation techniques. (Listen.) Here are the first eight bars of the theme:

Like the Chopin example above, Mozart first variation decorates and elaborates the plain melodic line:

The fifth Variation breaks up the steady pulse and creates syncopated off-beats:

The seventh variation introduces powerful new chords, which replace the harmonies originally implied by the theme:

In the elaborate 8th Variation, Mozart changes from the major to the minor mode, while combining three techniques: counterpoint, suspensions and imitation:

Variation techniques are frequently used within pieces that are not themselves in the form of Theme and Variations. For example, Debussy’s piano piece “Reflets dans l’Eau” (1905) opens with a sequence of chords:

- that opens out into arpeggios when it returns later in the piece:

Sometimes melodic variation occurs simultaneously with the original. In Beethoven’s "Waldstein" piano sonata, the main ‘second subject’ theme of the opening movement, which is in sonata form, is heard in the pianist’s left hand, while the right hand plays a decorated version. (See also heterophony.)

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