We will never know exactly why Johann Sebastian Bach composed his Mass in B minor.
While Latin Church music was occasionally still performed in Protestant Leipzig, there was little opportunity for the performance of an entire Catholic mass.
Although we don't know why Bach took the time to complete this monumental composition, we have a good idea at least of how he intended the first two movements to be perceived.
In 1733, Bach included the Kyrie and Gloria in a petition for a courtly title addressed to the Catholic Elector of Dresden.
In a sense, these movements were a job interview-a display of skill from a composer who, although he had left his student days long behind him, was not above the challenge of a musical exam.