There’s a wonderful exhibition at the Dulwich Picture Gallery called “Rembrandt’s Light”, looking at not just his paintings but ink sketches and etchings. What it sets out to demonstrate is the essential theatricality of the artist and the extraordinary effectiveness of his use of the play of flames or sun or moonlight on figures and interiors and landscapes.

But what the exhibition also demonstrates is a kind of theology of light. Obviously, the Gospels, pre-eminently the Gospel of John, make enormous play with light and darkness: there is something inescapably creepy about that observation in John after Judas had taken the sop at the Last Supper and left “… and it was night”. As the late Henry Chadwick observed in a sermon, you could almost hear the dot-dot-dot following that.

There are extraordinary scenes here: the most dramatic is The Denial of Saint Peter, where Peter is accosted by the servant girl who accuses him of being a follower of Christ. Peter’s face is lit by the lamp held behind the maid’s hand. It’s only when you scrutinise the work closely and the eye is not distracted by that primary light that you notice there’s another, more diffused light in the corner and it shows Christ, turning towards Peter. At first glance I didn’t see him at all. Duh!