Four Duetti, BWV 802-5

All we know for certain about the four Duetti is that they were first published in Part 3 of the Clavierübung in 1739. What they are doing there, a set of essentially two-part inventions in a book of sixteen pieces otherwise clearly intended for the organ, is a matter for conjecture. Theories vary between the mundane and the fanciful. At one extreme their inclusion is dismissed as a mistake - which seems unlikely, since the composer compiled and published the whole thing himself. At the other extreme they are held to be symbolic of Luther’s four rules for helping ministers teach the Christian doctrine - which is difficult to believe even if it is accepted that the collection was assembled as an anthology of music suitable for the Lutheran daily liturgy.

From the strictly practical point of view, however, it doesn’t really matter what function they might have had or even whether they were originally intended for the organ or the harpsichord. Economically but imaginatively written as fugues in two parts, they sound just as convincing on either instrument or, indeed, on the piano. Each has its own structure and its own character. Duetto No.1 in E minor, for example, includes two modest bravura episodes between the three fugal passages, while No.2 in F major is in ternary form with an ingenious middle section based on a chromatic secondary theme together with a variant of the fugue subject. The third and fourth Duetti, a pastoral invention in G major and a more intellectual argument in A minor, are distinguished by the simplicity of the main theme of the one and the complexity of that of the other.