When Johann Sebastian Bach set himself to work on a new composition, it was normally just a matter of days, at most a week or two, before it was finished. Such was certainly not the case with his Mass in B Minor, BWV 232. The fourth part (Sanctus) dates from 1724; the first two parts (Kyrie and Gloria) were completed in 1733; the third part (Credo), as well as the work’s final autograph score, date from 1748, just two years before the master’s death. We do not know why it took him so long to complete this magnificent mass, nor do we know why he composed it to begin with. There was neither occasion for its performance nor commission for its composition. As a mass it was much too vast (more than 2 hours) for liturgical use, and it certainly had no place among the secular music performed in the courts of Baroque Europe. As it turned out, the mass was never performed in its entirety during Bach’s lifetime. It’s possible he never intended it to be performed at all.

  The mysteries of the B Minor Mass’ raison d’être, composition and origins have long been part of the work’s magic. Some of the movements comprise highly effective recasting of earlier Bach works (mainly cantatas), while others are completely unique to the mass. The wide range of styles Bach employed have led some to believe that he specifically set about composing a work that could stand as the summation of his entire oeuvre. This may or may not have been his goal, but there is no disputing the fact that everything that made Bach the master composer he was can be evinced in the B Minor Mass. This cannot be said of any of his other works.

  The range and depth of moods in the work are astounding: The brooding Kyrie seizes you by the lapels; the Gloria excites with its celebratory brass motifs and concludes with an inexorable, propulsive Cum Sancto Spiritu fugue; the Sanctus opens with great majesty, crackles with the energy of its two Osana in excelsis movements and concludes with the grandeur and power of Dona nobis pacem (“Grant us peace”).

  Bach’s autograph score betrays a trembling hand not to be found in his other manuscripts. With nothing more to prove or gain, he devoted his remaining energies and time to this mass—a sort of spiritual testament, perhaps. For more than 260 years now, musical scholars and historians have practically fallen over themselves in praise of the work. Perhaps none sum it up more accurately and succinctly than the great German maestro Otto Klemperer (1885-1973): “For me, Bach’s B Minor Mass is the greatest and most unique music ever written.”

  Bach’s B Minor Mass will be performed by the Milwaukee Symphony Orchestra and Chorus, with soloists Hyunah Yu (soprano), John McVeigh (tenor), Nancy Maultsby (mezzo-soprano) and Jason Grant (bass). MSO Music Director Andreas Delfs will conduct the performance, which takes place May 23-24 at Uihlein Hall.