Piero’s Dream of Constantine part of the True Cross Cycle ~1460. Compare the adjacent stained glass window to the light generated from within the fresco — a night scene

I was mesmerised by it since adolescence, but was still awe-struck when I first saw it live. The expressions on their faces... The light. The intense, vivid stillness of that painted night; you can almost hear and feel them breathe - and it's all just pigment on plaster. What a genius.

Pull back to see Constantine in situ