Firm and dry-eyed before the lordly canvas."
See the article on Orvieto in my Sketches in Italy and Greece.
The earlier frescoes of Fra Angelico, on the roof, depict Christ as Judge. But there is nothing in common with these works and Signorelli's.
This is the conjecture of Signor Luzi (Il Duomo di Orvieto, p. 168). He bases it upon the Dantesque subjects illustrated, and quotes from the "Inferno":—