Publisher Desc.  Du und Du (Thou and Thou, or alternatively, You and You), opus 367, is a waltz composed by Johann Strauss jr. in 1874. The waltz features themes from the operetta Die Fledermaus. The title of the piece, as well as one of its melodies, was taken from the famous Dui-du chorus in Bruderlein, Bruderlein und Schwesterlein.