Bach composed the first version of this piece in 1723 using the key of E-flat major for the Christmas Vespers in Leipzig which contained several Christmas texts. Over the years he removed the Christmas-specific texts to make it suitable for year-round performance, and transposied it to D major, providing better sonority for the three trumpets, which is the standard version of the work encountered today. The Magnificat is divided into twelve parts which can be grouped into three movements, each beginning with an aria and completed by the choir. The four movements from the original version have...