: ▁ 2 5 ▁December ▁ 1 7 3 4 : ▁Part ▁I ▁– ▁' ear ly ▁in ▁the ▁morning ' ▁at ▁St . ▁Nicholas ; ▁' in ▁the ▁afternoon ' ▁at ▁St . ▁Thomas ▁ 2 6 ▁December ▁ 1 7 3 4 : ▁Part ▁II ▁– ▁morning ▁at ▁St . ▁Thomas ; ▁afternoon ▁at ▁St . ▁Nicholas ▁ 2 7 ▁December ▁ 1 7 3 4 : ▁Part ▁III ▁– ▁morning ▁at ▁St . ▁Nicholas ▁ 1 ▁January ▁ 1 7 3 5 : ▁Part ▁IV ▁– ▁morning ▁at ▁St . ▁Thomas ; ▁afternoon ▁at ▁St . ▁Nicholas ▁ 2 ▁January ▁ 1 7 3 5 : ▁Part ▁V ▁– ▁morning ▁at ▁St ▁Nicholas ▁ 6 ▁January ▁ 1 7 3 5 : ▁Part ▁VI ▁– ▁morning ▁at ▁St . ▁Thomas ; ▁afternoon ▁at ▁St . ▁Nicholas ▁ ▁Text ▁ ▁The ▁ease ▁with ▁which ▁the ▁new ▁text ▁fits ▁the ▁existing ▁music ▁is ▁one ▁of ▁the ▁indic ations ▁of ▁how ▁successful ▁a ▁par ody ▁the ▁Christmas ▁Or atorio ▁is ▁of ▁its ▁sources . ▁Music ologist ▁Alfred ▁D ür r ▁and ▁others , ▁such ▁as ▁Christoph ▁Wol ff ▁have ▁suggested ▁that ▁Bach ' s ▁som etime ▁collabor ator ▁Pic ander ▁( the ▁pen ▁name ▁of ▁Christian ▁Friedrich ▁Hen r ici ) ▁wrote ▁the ▁new ▁text , ▁working ▁closely ▁with ▁Bach ▁to ▁ensure ▁a ▁perfect ▁fit ▁with ▁the ▁re - used ▁music . ▁It ▁may ▁have ▁even ▁been ▁the ▁case ▁that ▁the ▁Christmas ▁Or atorio ▁was ▁already ▁planned ▁when ▁Bach ▁wrote ▁the ▁sec ular