I listen to music. So much music, new and old and strange. I do not understand music at all. Stories I understand, but the language of music is opaque to me. Then I sit in an old pumping station by the river and listen as a man weaves the two together: old Bach and his battle with Frederick. How marvellous. And the more so, because Bach’s barbed riposte was so much more than just a skewering. To discover the composer’s answer, the king had to change his very identity, fill his mind with all the things Bach believed should be there. Rewriting his code.