Invention
Two-part keyboard piece by Bach.
What it means
The inventions are the two-part keyboard pieces of Johann Sebastian Bach that he compiled, together with the three-part sinfonias, as a collection for teaching. The name goes back to the rhetorical term of invention and means the musical idea from which a piece is developed. Bach's own preface names as aims to learn playing with both hands, to gain good ideas and carry them out, and to acquire a singing manner of playing.
Musical use
The layout is terse: a short motif appears at the beginning, is taken up by the second voice, and is transposed, inverted, shortened, or extended in the course. Unlike the fugue, the inventions follow no fixed scheme of exposition and development, but their work is just as consistent. For teaching they remain central to this day, because they occupy both hands equally and train the hearing of several voices at once. Musically they show in the smallest space how a closed piece arises from a single idea.
Other names
Erfindung (“invention”) is the German translation of inventio. The term comes from rhetoric, where it designates the finding of a thought.
Performance practice
Mark all appearances of the motif and play them with the same articulation, in both hands. Practise the voices first individually and then together, but listening, so that none sinks to accompaniment. Use no pedal or very little; the clarity of the voices is the main thing. Fix articulation and ornaments in writing instead of inventing them anew each time. Watch the cadences: they articulate the piece and give it form.
Bear in mind that the collection has a pedagogical intention that is expressed in the preface: it is about clean playing with both hands, about dealing with musical ideas, and about a singing manner of playing. Practise therefore every voice as you would sing it. Mark all motif entries and keep their articulation the same. Ornaments belong to the substance and should be executed according to the indications of the time. Play without pedal and watch the cadences, because they articulate the piece.