O ewiges Feuer, o Ursprung der Liebe (O eternal fire, o source of love), BWV 34.2 (formerly BWV 34a) is an incomplete wedding cantata composed by Johann Sebastian Bach, of which only the complete libretto and some parts (movements 2, 3 and 6) have survived.
[1] The cantata was composed in Leipzig most likely in 1725 or 1726,[2] or 1727 or later,[1] as a wedding commission, and performed shortly after its composition.
The piece is scored for four vocal soloists (soprano, alto, tenor, bass) and four-part choir, two oboes, two flauti traversi, timpani (tamburi), three trumpets (trombe) in D, two violins, viola, and basso continuo.
This is followed by a short secco bass recitative ending on an imperfect B minor cadence.
The third movement exists only in reconstructed forms; it likely opened with strings and continuo.