The work is now performed every Good Friday in the Thomas Church at Leipsic. The organ gallery occupies the whole of the west end of the nave and two side aisles. On each side are placed the singers, the soprano and alto parts being sung by women. This chorale is sung by the boys of the Thomas Schule, some forty in number, and the effect of the contrast of tone bringing it in is overwhelming. Poor Bach, with his miserable little rabble of a choir with three voices to a part, can hardly have realised how his music would sound many years after his death, when performed by a large body of enthusiastic and intelligent musicians.
The next chorale in the work is
harmonised for four voices, and accompanied by violins, flutes, oboes, violas and basses, in unison with the respective voices and figured bass organ part. This accompaniment is used for all the succeeding chorales, and we may remark that the melody is given to the two flutes and two oboes as well as the first violins, that it may be made prominent.
All the other chorales in this work, six in number, are thus arranged and accompanied. The well-known Phrygian melody
occurs no less than five times, sometimes harmonised in the Ionian, sometimes in the Phrygian mode, and he has arranged it in the latter mode as a very beautiful vorspiel for the organ (Peters 244, No. 27).
We may here remark that in playing the organ choral-vorspiele no notice is to be taken of the fermata, which are only used when the melodies are sung.[58]
Uses of the Chorale
Besides the choral-vorspiele, and the introduction of the melody in conjunction with a chorus, and the harmonisation in four parts, with orchestra doubling the voice parts, Bach makes many other uses of the chorale. In the Christmas Oratorio, for example, he combines it with recitative, the melody being freely accompanied by the orchestra, and interspersed with recitative passages of the nature of interludes between the lines. Or he harmonises it in four parts, with free orchestral interludes.