Mahan Esfahani is unquestionably a latter-day philosopher of the harpsichord. And like any good philosopher, you may not always agree with him, but he is always interesting, never boring. So, he proves again here, with his epic new recording of a cornerstone of the keyboard repertoire, Book I of JS Bach’s The Well-Tempered Clavier. It’s quite the ride.

Esfahani combines philosophy with theatre while insisting on the integrity of the 24 preludes and fugues as a whole. As he writes in yet another brilliant, provocative booklet essay, “it should be listened to as one great piece rather than an assortment of smaller movements.” To emphasise this, he reprises here, as he does in concert, the opening C major prelude after the final B minor fugue.

Esfahani also rails against the Romantics’ ossification of Bach’s music while stressing the fugues’ latent dramatic qualities. One is “a great choir on a feast day”; another, “the 18th-century foreshadowing of the prelude to Wagner’s Die Meistersingers.”

Much of the recording’s...