Bach

If you look for Bach in Wikipedia or any good modern encyclopedia, you'll get something like:

"German composer, organist, violist, and violinist whose ecclesiastical and secular works for choir, orchestra, and solo instruments drew together the strands of the Baroque period and brought it to its ultimate maturity (...) unrivalled control of harmonic and motivic organisation, and the adaptation of rhythms, forms and textures from abroad, particularly from Italy and France (...) Revered for their intellectual depth, technical command and artistic beauty, Bach's works include etc (...) He is now regarded as the supreme composer of the Baroque, and as one of the greatest of all time...

Ok, fine, agreed. But I think Pablo Casals (listen to the link I put below) summarizes it in one sentences:

“To strip human nature until its divine attributes are made clear, to inform ordinary activities with spiritual fervor, to give wings of eternity to that which is most ephemeral; to make divine things human and human things divine; such is Bach, the greatest and purest moment in music of all time.”

http://www.youtube.com/watch?v=VhcjeZ3o5us