JOHANN Sebastian Bach is hard to forget on torture. He treats it rarely in his vocal works, but when he does, no composer matches his uncanny ability to evoke torture’s harrowing extortion of truth and lies, the shattering recriminations it visits on both the tortured and the torturer. This is not music of the lash and the rack, but of mental terror.

Many interpreters of Bach’s cantatas and their libretti might claim that references to torture in these works are merely metaphorical, convenient literary weapons used to make religious arguments about morality and salvation. But then as now, torture was an omnipresent, much-debated practice, thought to be a crucial means not so much of establishing guilt but of confirming it.