Mr. Cooper, who is best known for his zesty performances of Bach’s chamber music, is also a musicologist of no mean accomplishment. Besides preparing scholarly editions of harpsichord music, he has been, as of late, in the reconstruction business: finishing or recreating works by masters from mere fragments. Last year he reconstructed the violin part to Mozart’s Adagio Quasi FantasiaK.396/385f from an extant five measures in Mozart’s hand. He has also reconstructed the original cadenza for Beethoven’s B-flat piano concerto. Tonight, we heard a United States première of Mr. Cooper’s extensive reconstruction of a wedding cantata by J.S. Bach, listed in the Schmieder’s catalogue as #216.