a musical form based on the variation of a theme (sometimes two or even three themes) written by the composer or borrowed by him, hence the name “theme with variations,” which is often given to works in this form. The source of variations lies in folk composition, in the alterations that a song form undergoes with the repetition of couplets. The theme of variations is usually simple in manner of execution and is performed at a moderate tempo, which allows the introduction of the successive textural, tempo, and genre changes into the variations. There are variations that maintain the structure of the theme (variations on basso ostinato, on a sustained melody, or strict variations) and those that alter it (free variations). In the first case, the modification affects all or several elements of a theme: the melody, manner of execution, and polyphonic texture; in the separate variations, the harmony, tempo, and measure (Passacaglia in C minor of J. S. Bach, Beethoven’s 32 Variations for Piano, the Persian chorus from Glinka’s opera Ruslan and Liudmila). In the second case, the variations are linked to the theme by general melodic turns but change the genre, measure, tempo, and structure, resulting in a suitelike form (Schumann’s Symphonic Etudes for Piano, the second part of Tchaikovsky’s trio Memories of a Great Artist, the second part of Prokofiev’s Concerto No. 3 for Piano). It is possible to unite both forms of variation (the finale of Shostakovich’s Sonata No. 2 for Piano). Sometimes, as is evident from the examples, the variations form an integral part of a sonata, symphonic cycle, or other musical form.