Scholars have always puzzled why Bach, having presented the Kyrie and Gloria of the B minor Mass to Augustus II, the elector of Saxony and king of Poland — almost as a job application at the Catholic Dresden court — went on to expand it to a length unsuitable for liturgical use towards the end of his life, recycling material from earlier works. It stands as Bach’s last will and testament in the field of religious music, and it seems pointless arguing how it should be performed when it was not heard in its entirety until more than a century after Bach’s death. One might expect Cohen’s Arcangelo to opt for minimal personnel — although the trumpety movements suggest spectacular forces — but his choir of 20 can convey the inward spirituality of Et incarnatus est and the laudatory éclat of the Gloria and Et resurrexit with equal efficacy. The excellent high-voiced soloists are Lydia Teuscher and Ida Falk Winland, duetting sensuously in the Christe eleison, and Tim Mead’s rapt alto in Qui sedes and Agnus Dei. Samuel Boden’s lithe tenor and Neal Davies’s solid bass blend ideally with their colleagues.