Here is a dark room in Kelvingrove Art Gallery in Glasgow, in which hangs one of the most remarkable 20th-century depictions of the Crucifixion. Painted in 1951, Christ of St John of the Cross sees Salvador Dalí jettison his surrealism in favour of Renaissance methods to depict Christ, hanging —no nails, no thorns — merely the Cross, the Saviour, and the world.

The painting is notable for the impact it has on those who go to see it. It is valued at over £60 million, but the primary threat to the painting is not thieves but assault — it has been attacked twice. Viewers who see it often report peculiar psychological effects. Regardless of what brings you there, re­gardless of your outlook, or the lens through which you arrive at it, it seems that meditat­ing on the Cross brings something profound out of us.