Johann Sebastian Bach was a talented composer of the Baroque Period. Apart from writing hundreds of amazing pieces, he was the first to teach students the rule of curving the fingers while they play and to use all of the fingers. His largest work was the two-hour Mass in B Minor, in which he gloriously depicted the life of Christ. Today he is considered one of the most important composers in the history of music.
Bach was a devout Lutheran and his goal in life was to compose "well-regulated church music to the glory of God". He began his sacred pieces with "JJ", Jesu Juva in Latin-- in English, it means "Jesus, help". And he ended with "SDG": To God alone the Glory.