section_path: Life/Leipzig (1723–1750)/Middle years of the Leipzig period (1730–1739)
section_name: Middle years of the Leipzig period (1730–1739)
paragraph_text: Middle years of the Leipzig period (1730–1739)
  
  In 1733, Bach composed a Kyrie–Gloria Mass in B minor which he later incorporated in his Mass in B minor. He presented the manuscript to the Elector in an eventually successful bid to persuade the prince to give him the title of Court Composer. He later extended this work into a full mass by adding a Credo, Sanctus, and Agnus Dei, the music for which was partly based on his own cantatas and partly original. Bach's appointment as Court Composer was an element of his long-term struggle to achieve greater bargaining power with the Leipzig council. Between 1737 and 1739, Bach's former pupil Carl Gotthelf Gerlach held the directorship of the Collegium Musicum.
  
  In 1735, Bach started preparing his first organ music publication, which was printed as the third Clavier-Übung in 1739. From around that year he started to compile and compose the set of preludes and fugues for harpsichord that would become his second book of The Well-Tempered Clavier. He received the title of "Royal Court Composer" from Augustus III in 1736.