Johann Sebastian Bachs zweistimmige Inventionen in d-Moll (BWV 775) und h-Moll (BWV 786) als instrumentale Klangreden

A pair of Two-part Inventions by Johann Sebastian Bach (No. 4 in D minor, No. 15 in B minor) is analyzed according to the rhetorical principles established in Johann Mattheson's Capellmeister, which, for its part, is apparently based on a treatise by Christoph Weissenborn. Exemplifying the disposition of Roman oration (exordium, narratio, propositio, confirmatio, confutatio, conclusio), each of the two inventions, understood as instrumental speech in tonal form, possesses nonetheless a unique and individual design. Beginning as a canone infinito or circulare, Invention No. 4 resolves the ongoing movement by integrating the subject and its inversion into two hemiolas, the first of which employs a false ending that all the more emphasizes the second and final hemiola's regular cadence. Each of Invention No. 15's initial four statements (out of a total of six) ends with a weak cadence. A second level of "argumentation" connecting two of the first four parts of the disposition leads to the conclusion using a sequence of the subject and its cadenced repetition.