This is a clever, learned and occasionally baffling book that has the great merit of persuading us to look more closely at familiar paintings. Take, for instance, Christ on the Cross by Velázquez. This is perhaps the finest of all crucifixion paintings, and certainly the most interesting. It is one of the few that concentrate entirely on the Christ figure, rather than the surrounding characters in the story, or the scene as a whole. Moreover, Christ has long brown hair, which completely obscures the right side of his face. The tradition is that Velázquez lost his cool when painting the hair and threw his brush at the canvas. I don’t believe this. Nor does James Hall. His explanation is that the painting stresses the incarnation, the physical fact that Jesus is man as well as God. The right or Godly side of the face is ‘blinded and occluded’, while the manly or ‘worldly’ left side remains ‘fully visible and nakedly incarnate’.