JS Bach is one of a very small collection of composers who seem incapable of writing second-rate music. His Lutheran Masses are a perfect illustration of this: overshadowed by his monumental B Minor Mass, they nevertheless contain what might conceivably be his favourite music from the cantatas, lovingly revived in succinct works of vibrant colour and indefatigable inspiration. Loved by all who know them, they give the lie to the idea that the devil gets all the best tunes. The…