An "invention" is a short, original idea (Latin inventio) that, in musical terms, could be thought of as a motive. Bach's Inventions for keyboard are the best known musical works in this genre. They are short pieces based on a single idea--the "invention"--that is subjected to various melodic and contrapuntal manipulations. An invention is, therefore, both a musical piece and an illustration of compositional techniques. Bach's inventions are in two voices. A companion set of pieces in three voices are called "sinfonias." Construction Opening (the Exposition) Using Bach's keyboard inventions as models, we might categorize their beginnings as being in canon, featuring a contrapuntal "associate" against the main motive, or presenting the motive with a simple accompaniment. Canonic: Numbers 1, 2, 3, 4, 8, 10 Contrapunal Associate: Numbers 5, 6, 7, 9, 11, 12, 13 Accompaniment: Numbers 14, 15 Post-expository Sequel Some inventions continue with a reëxposition of the original material, in a closely related key (e.g. the dominant) and with parts reversed. Other inventions do not have such a reëxposition; rather, after an initial exposition they continue in a variety of ways: Reëxposition: Numbers 1, 6, 8, 9, 10, 11, 13, 14 Non-reëxposition Numbers 2, 3, 4, 5, 7, 12, 15 Back to Music 103 home page...