'They’re the most astonishing, beautifully conceived and tenderly painted scenes in early Renaissance art.'

Italy: 'The Dream of Constantine', 'History of the True Cross' fresco by Piero della Francesca (painted between 1447 and 1466), Bacci Chapel, Basilica of San Francesco, Arezzo, Tuscany (2016)

‘The Dream of Constantine’ by Piero della Francesca (1415/20-92). Fresco, 10½ft by 6ft; painted between 1447 and 1466 in the Bacci Chapel, Basilica of San Francesco, Arezzo, Tuscany. Picture from History/David Henley/Bridgeman Images.

The Dream of Constantine by Piero della Francesca

‘I first saw the Piero frescoes in Arezzo nearly 30 years ago, and I’ve visited and revisited many times since. They’re the most astonishing, beautifully conceived and tenderly painted scenes in early Renaissance art.

The Dream of Constantine faces you immediately at eye level as you enter the chapel. Beautifully restored about 20 years ago, it glows with internal light. Somehow, the radiance of the angel holding a cross spreads luminescence across the figures of the painting, with the soldier on the left backlit in silhouette.

‘The stars are still glimmering in the sky; this is dawn and the colours – dusky pink and yellow for the tent, a gorgeous red for the bedclothes, the white sheet, the blue trim and crimson stockings of the seated figure – stand out vividly. I’m certain this vignette is by Piero himself and it is assuredly the artist at his very best ’

Chris Smith is a former Secretary of State for Culture, Media and Sport. He is now Lord Smith of Finsbury and Master of Pembroke College, Cambridge.

John McEwen on The Dream of Constantine

The 10-part cycle of frescoes that shows The Legend of the True Cross and proclaims the high altar in the church of San Francesco, Arezzo, announces della Francesca’s artistic maturity and is his most substantial work. This, the third chosen for our ‘Favourite Painting’ series, is fifth in the cycle, which tells the story of the Cross on which Christ was crucified, the wood of which had grown from a seed of the fatal apple tree in the garden of Eden.

The scenes on the right walls of the chapel show those who were not – or not yet (Constantine) – Christians. The choice of subject for the cycle – the veneration of the Cross – was no doubt made by the Franciscan friars, whose church it was. Their founder, St Francis, had seen a vision of a golden Cross over Arezzo in 1211, after the citizenry had been exorcised of the devils responsible for the prevailing civil unrest.

Fresco cycle The Legend of the True Cross by Piero della Francesca in Italian Gothic Basilica di San Francesco (Basilica of San Francesco) in Historic

Fresco cycle The Legend of the True Cross by Piero della Francesca in the Basilica di San Francesco in Arezzo. Picture by Alamy.

The Bacci family, local merchants, paid for the commission, selling a vineyard to raise the cash. The offer was to pay someone ‘to paint and make figures in the Cappella Magiore’.

Bicci di Lorenzo, an old artist, was first commissioned, but he died soon after starting and Piero took over. As usual in such cases, he was helped by assistants, the hand of Giovanni di Piamonte being most identifiable.

This fresco, one of the earliest nocturnes in art, shows Constantine dreaming of an angel bearing a dazzling celestial cross. He accordingly bore an emblematic cross on his shield and proceeded, after victory at the Milvian Bridge, to become sole Roman Emperor and the first to convert to Christianity.