The Signature of Humility

At the end of nearly every manuscript he completed — cantatas, fugues, the Mass in B Minor — Johann Sebastian Bach wrote three small letters in the margin: S. D. G. Soli Deo Gloria. "To God alone be the glory." This was no empty flourish. Bach composed over a thousand works across his lifetime, music so mathematically precise and spiritually luminous that later composers wept when they discovered it.…