In the four compartments of the vault in the entrance bay the artist portrays the four Doctors of Church together with their scribes: in the south (at the top of the illustration) St Augustine and opposite him, St Ambrose; in the east (to the left) St Jerome, and in the west St Gregory. The architectural structures jut up from below into the gold background. The painter conveys a definite idea of the intellectual work of these saints through the great attention to detail and the perspectival accuracy.