Composers: Secure in the Universe

Johann Sebastian Bach seemed to have no understanding of his own greatness. Year after year, he turned out his glorious cantatas and Passions like a baker hurrying over the breakfast rolls. He considered the music that flowed from his pen for 50 years to be a collection of testimonials to honest craftsmanship—some of it better than others, but all of it composed, as he humbly wrote in the dedication of the Musical Offering, "as well as I possibly could."

He gave little thought to the preservation of his works, and the scores he left behind contain few indications of the...