Oil paint, with its extraordinary power to capture sheen and shadow, to make darkness visible, allows Philippe de Champaigne to reveal a key aspect of this child’s nature. As five shepherds draw near to the manger, set near the mouth of a cave, the flame of their torch pales. They, and the entire earthly scene, are illuminated by the swaddled child who is to be the light of the world, shining in the velvety darkness which will not overwhelm it. He is surrounded by the brilliant blue robe of his mother, painted with the most expensive of pigments, ground lapis lazuli: and to show that she is uniquely favoured among women, the colour reappears in the drapery of the heavenly host, who have accompanied the shepherds to Bethlehem, and are still singing.

Significantly their song, written on the fluttering banderole, continues beyond the words reported by Luke: clearly legible, the letters that climb into the cloud at the top right spell LAUDA (MUS TE). ‘We praise you’. The angels have moved from the gospel into the Gloria of the Latin mass. Like all who look at this painting, the angels watch both the birth of Christ centuries ago, and the perpetually present mystery of his sacrifice in the liturgy of the church.

On the ground, his white fleece painted with tender precision, his feet bound for the slaughter, a lamb looks silently out at us. He is the gift of the worshipping shepherds, pointing to the sublime paradox that this child will be at once the Good Shepherd and the Lamb that is slain.

When the priest celebrating Mass in front of this altarpiece held up the host, the congregation looking at it would, behind it and beside it, behold the Lamb of God that takes away the sins of the world.