The Golberg Variations BWV 988 by J. S. Bach, is an excellent example of variations in the baroque period. It is a work of great proportions based on a theme titled Aria followed by 30 variations.

• The variations follow the formal and harmonic plan of the Aria
• Variations 3, 6, 9, 12, 15, 18, 21, 24 and 27 are canons, starting with a canon at the unison and ending with a canon at the ninth
• Variation 10 is a fughetta
• Variations 15, 21 and 25 are in minor mode
• Variation 16 is an overture
• Variation 30 is a quodlibet, a composition that combines several known melodies
• The Aria is repeated after the variations

The Aria is in binary form. Each part is made of two phrases:

• In part A, the first phrase is in G major and the second phrase modulates to D major (dominant key)
• In part B, the first phrase is in G major and modulates to E minor (relative minor key) while the second phrase returns to G major
• Every phrase ends with a cadence to the tonic of G major, D major, E minor and G major keys

Here is the structure of the Aria:

All variations follow this structure (we will discuss minor variations later). Most sections have 16 measures, but in some variations, two measures are combined into one, so each section has only eight measures. In variation 16 (overture), part B has 32 measures. In this case, two 3/8 measures of part B correspond to one measure in the Aria.

The Aria or theme:

Shelley Katz, piano. Recording courtesy of MUSOPEN and Shelley Katz.

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Some harmonic variations of the original are found. Here we compare the Aria and the first variation with variations marked in red:

Key	G major									D major
Measure	1	2	3	4	5	6	7	8	| 9	10	11	12	13	14	15	16
Aria (theme)	I	V	vi - vii / V	V	I - V / IV	ii	V	I	I - vii / re	I	ii	V	I - V / IV	IV - ii	V	I
Variation 1	I	V	vi - V / V	V	I	ii	V	I	I	iii	ii	V	I	IV - ii	V	I

Measures 17 to 32:

Key	G major		E minor						G major
Measure	17	18	19	20	21	22	23	24	| 25	26	27	28	29	30	31	32
Aria (theme)	V	I	VI - ii	V	i	VI	ii - V	i	ii	I	ii	V	I - V / IV	IV	V	I
Variation 1	V	I	iv - ii	V	i	iv	V - vii/V - V	i	ii	I	ii	V	I - V / IV	IV - V - vii/ii - ii	V - I - V	I

First Variation

Minor Mode Variations

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