Published 1739, no Autograph MS. Later copies only.

‘Duetto’

Some uncertainty as to a suitable name for imitative two-part pieces is suggested by the term ‘Praeambulum’ for works in the CbWFB later called ‘Invention’ in the fair copy of 1723. Theorists understood ‘duetto’ as (i) a ‘petit duo’ above a bass (Walther's Lexicon 1732, after Brossard's Dictionaire 1703), (ii) a dialogue aria with an ‘opportunity to introduce and develop two subjecta opposita’ (Mattheson, Critica musica II, 1725, p. 28), (iii) an instrumental or vocal piece above a bass, ‘skilfully fugued’ (ibid. I, 1722, p. 131), and (iv) a two-part piece incorporating more than mere ‘imitation at the unison and octave’ (ibid. pp. 305, 360). Although the last comes closest to BWV 802–805, it refers less to technique than to a form.

Only in general terms do the Four Duets allude to French organ duos, which in Grigny, Raison, Boyvin and Du Mage have no more than a loosely organized counterpoint. Similarly, in length and idiom they go far beyond the two-part fugal verses in Pachelbel's Magnificats. In Cantatas 140 and 110, ‘duetto’ is a dialogue or duet plus bass. In the search for wider significances in Clavierübung III, Lutheran devotional dialogues have been invoked to explain the term: that between pastor and pupil in the catechism (Humphreys 1994 p. 48), or between the Soul, the Word, Cross, Death and Heaven in the influential Geistliche Erquick-Stunden, 1672 (Clement 1999 p. 320).