IT IS an extraordinary experience to stand in the nave of the basilica in St Catherine’s Monastery in the Sinai desert, and to look up at the sixth-century mosaic of the Transfiguration glittering in the apse behind the altar.

The transfigured Christ is encased in a dark, egg-shaped mandorla. Moses and Elijah stand pointing to him on either side, while the disciples James and John kneel with their hands raised in astonishment and worship. Peter, meanwhile, lies at Jesus’s feet, his chin in one hand, as though he is just waking up, and rather puzzled at what is going on. One knee appears to be on the very edge of the semi-circular frame, as though he might tumble out of the mosaic altogether and end up with a bump on the floor of the church.

We don’t make much of the Transfiguration in the Church of England. Falling in August, and rarely on a Sunday, it has little impact. In the lectionary, one of the Gospel versions of the story is appointed for the Sunday before the beginning of Lent, suggesting that the point of the feast is to give a glimpse of Easter before the rigours of Lent.

But, in Orthodoxy, the Transfiguration is one of the 12 great feasts of the calendar, and has a wider meaning than we would usually ascribe to it. In the earliest traditions, any monk aspiring to be an iconographer had to begin with the Transfiguration, to train himself to see the light that radiated from Tabor, and to which a true icon is a portal.

The depiction of Peter in the Sinai Transfiguration is a warning as well as a witness. Our eyes need to be trained to grasp the faith of the Trinity: God visible and invisible, hidden in light and yet transparent to the eyes of faith. Put simply, the message is that we are held in God’s presence as long as we keep looking at Jesus. Christ stands within God’s uncreated light, the light in which all human living and dying takes on its true meaning.

Two novels have helped me this year to train my eyes on the unseen: Francis Spufford’s Light Perpetual, now longlisted for the Booker Prize (News, 30 July, Books, 19 February), and Catherine’s Fox’s Tales from Lindford (Summer Books, 30 July). Both have been like water in the spiritual desert of Covid. They reminded me of how Cicely Saunders, who initiated the hospice movement, used to speak of carrying on in difficult times with “no visible means of support”. She put the emphasis on the word “visible”, because the invisible means of support were what sustained her. Like Peter, we may end up on the edge of the picture from time to time, but we can hope not to end up completely on the floor.