existing vocal music to a new text) appear in an unfavourable light" while it was "almost unavoidable" in Bach's day. He further notes that "by abstracting movements from what he evidently considered some of his finest vocal works, originally performed for specific occasions and Sundays within the Church's year, he was doubtless attempting to preserve the pieces within the more durable context of the Latin Ordinary." Details of the parodied movements and their sources are given below. I. Kyrie and Gloria ("Missa") Kyrie eleison (1st) Five-part chorus (Soprano I & II, Alto, Tenor, Bass) in B minor, marked Adagio (in the four-bar choral introduction) and then Largo in the main section with an autograph time signature of or common time. Joshua Rifkin argues that, except for the opening four bars, the movement is based on a previous version in C minor, since examination of autograph sources reveals "a number of apparent transposition errors". John Butt concurs: "Certainly, much of the movement—like many others with no known models—seems to have been copied from an earlier version." Butt raises the possibility that the opening four bars were originally for instruments alone, but Gergely Fazekas details a case, based on manuscript, historical context, and musical structure, that "Bach might have composed the present introduction in a simpler form for the original C minor version" but "might have made the inner texture denser only for the 1733 B minor version." Christe eleison Duet (Soprano I & II) in D major with obbligato violins, no autograph tempo marking, time signature of . Kyrie eleison (2nd) Four-part chorus (Soprano, Alto, Tenor, Bass) in F minor, marked alla breve, and (in the 1748–50 score) "stromenti in unisono". Autograph time signature is . George Stauffer points out (p. 49) that "the four-part vocal writing ... points to a model conceived outside the context of a five-voice Mass." Note the nine (trinitarian, 3 × 3) movements that follow with a largely symmetrical structure, and the Domine Deus in the centre. Gloria in excelsis Five-part chorus (Soprano I & II, Alto, Tenor, Bass) in D major, marked Vivace in the 1733 first violin and cello parts, time signature. In the mid-1740s, Bach reused this as the opening chorus of his cantata Gloria in excelsis Deo, BWV 191. Et in terra pax Five-part chorus (Soprano I & II, Alto, Tenor, Bass) in D major, no autograph tempo marking, time signature of