“Bach is the beginning and end of all music.” Max Reger’s tribute to the great Baroque composer might also serve as a motto for the concert series performed by Sir András Schiff in late December and early January. Starting in the hall’s opening season in 2017, Schiff has presented a multi-year cycle of Bach’s keyboard works at the Pierre Boulez Saal. The project now comes to its conclusion with a grand reprise that offers audiences the unique opportunity to experience Bach’s artistry over the course of seven nights.