4. Vision of Constantine (detail)
by PIERO DELLA FRANCESCA, Fresco
A supernatural glow emanated by the heavenly envoy lights up the pink and yellow tones of the tent, the bed with the red cover and the white sheet; it strikes the soldier with the iron helmet facing on the right, and its reflection creates an extraordinary backlit effect on the sentry to the left, seen from the back, leaning on his spear.