J.S. Bach's first biographer, Forkel, tells that young Johann Sebastian discovered that his brother had in his music cabinet a special book of compositions by some of the more established composers of that day, such as Pachelbel, Froberger, Bohm, and Buxtehude. He wanted to borrow the book, but for some reason his brother refused. Perhaps brother Johann Christoph was reserving those pieces for his own study or performances and didn't want the talented youngster in his home to perfect the works first.
Johann Sebastian clearly coveted his brother's book, however, and in the middle of the night, when everyone else in the house was asleep, he crept down to sneak the anthology from the cabinet. He took it to his room and began to copy it by moonlight! It took him six months. Johann Christoph found out about it...and promptly impounded the copied volume. (Johann Sebastian did not get the book back until his brother died almost a quarter-century later.