Originally a chorale written by Martin Luther, founder of Lutheranism, Bach transforms "Nun komm, der Heiden Heiland" from a church hymn to a cantata masterpiece. Now don't get me wrong, Luther's original piece was integral in making tonal harmony standard among composers of his day (basically bringing western music out of the dark ages), but Bach's version takes it to another level. The only real basis that Bach had for his take on the piece was a bit of the rhythmic pattern and the words, but he implemented techniques that were experimental for his time, like contrapuntal harmony and imitation. Another interesting fact about these cantatas that he wrote one a week. You read that correctly, one a week. Even though it was expected of him to perform a cantata each week as cantor of one of Leipzig's largest Lutheran churches, starting from scratch was all his idea. His mastery over music combined with his unparalleled work ethic made him the influential genius that he is recognized as today.
Got any favorite Baroque pieces?