Perino del Vaga worked for a time under Raphael, and during the 1520s became one of Rome’s leading fresco painters. This is a study for two of the Evangelists – St Mark with his lion, and St John with his eagle – painted by Perino in the vault of a chapel in San Marcello al Corso. The project was interrupted by the Sack of Rome in 1527 and was completed (by Perino’s assistant Daniele da Volterra) only in 1543.