The bishops who directed the affairs of each church presented themselves in public by drawing on images from humble figures of daily life. Among the Christian decorative motifs found on the utility oil lamps that provided household lighting is one such image. It is the picture of a man perched on a platform high up in a tree overlooking a grain field or an orchard. The figure is one drawn from everyday experience. He was the guardian of the cereal crops, the custos fructuum, or he was the watchman of the vineyard high up in his speculatorium vinitoris. This image of the good guardian was often evoked by bishops. In his abortive debate with Emeritus, the dissident bishop of Caesarea, Augustine defined who a bishop was: he was a man chosen by the people to lead them. Like the Lord himself, the bishop is stationed in a high lookout where he can see everything, high over the vineyards to guard the harvest. The elevated image of the lookout could be linked to the title of episcopus given to the bishop, which literally meant someone who oversees the welfare of others. In considering the term, Augustine explains:

The theme is elaborated again and again whenever the duties and the powers of a bishop are considered: he is a watchman, a guardian, and a lookout who protects his people and warns them about the dangers that threaten them.