Our eyes are drawn to the rather off-colour looking man raising his hands to the back of the group. He's a shade of grey for a reason.
His hands are raised for joy. A prophesy said that he would not die before seeing the Messiah. Signorelli paints the moment he realises he is in the presence of Christ and will die in peace.
Signorelli's wonderful tiled floor, with its simple geometric design and bright colours, leads us towards the main action.
Placed behind the altar, the painting would have been the backdrop to a priest celebrating mass.
Pattern and colour are everywhere in this scene; from the multicoloured floor to the green and pink marble-effect of the ceiling.
Something we can't fully appreciate is Signorelli's clever architectural setting. It is not imaginary. If we were able to visit the church of San Francesco in Volterra, we'd see how Signorelli designed the painting to fit perfectly in its surroundings.
The perspective falls into place when the painting hangs at its proposed height, the trompe l'oeil roundels and coloured marble combine to create the illusion of a recessed chapel.