When Bach took up the position as Kantor at the Thomaskirche in Leipzig in 1723, he could hardly have anticipated the indelible imprint his appointment would have upon the future of western classical music. One of his main duties was to compose liturgical cantatas for every Sunday and feast day of the church year, and in his first four years alone he composed an astonishing 150 cantatas. 300 years on from that historic appointment, we look back at his first cantata cycle in Leipzig, and the rich creative environment that surrounded him as he made musical history.