Though he was known in his own lifetime almost exclusively for his skills as an organist, Johann Sebastian Bach exerted inestimable influence on later composers. Credited with perfecting the Western tonal system that is still in use today, Bach was also an astonishingly prolific composer; during much of his tenure as Kapellmeister in Leipzig, he created a new five-movement cantata every other week in addition to writing masses, motets, and intricate keyboard exercises for his students.