Allegory of idolatry on the imitation-marble band around the lower part of the wall decoration

The sacred story developed in the narrative scenes is commented on and completed by a system of ornamental panels and bands, which are perhaps less famous than the narrative scenes but are equally important to the iconographic programme worked out by Giotto, probably with the help of a learned churchman.
The personifications of Virtues ancl Vices painted in monochrome on the fictive marble dado at the base of the nave walls perform a vital role in the symbolic system. The dado simulates marble even in its material consistency: it was produced by means of the difficult technique of 'stucco romano'.
The figures are placed almost at eye level, so that they might be thought of as occupying the same time zone as the spectator: while the sacred stories portray events that happened in the past, and the Last judgment anticipates an event in the future, the Virtues and Vices refer to the present, to everyday life.
Believers, on entering tbe Chapel - which, it should be remembered, was designed for a votive and penitential function - were meant to feeI directly involved and implicated. This is referred to explicitly by the face of St. Peter in the scene of Pentecost, the only one in the entire cycle of frescoes to look out at the spectator. From this final scene, the saint to whom the ministry of the Church had been entrusted turns to face those on earth, reminding them of the decisive choice to be made between good and evil.
The system of antinomies places the pairing of Justice/ Injustice at the centre, in the middle of the nave: these two monumental figures are seated firmly on thrones, and complemented by tiny scenes at the bottom which depict the serene unfolding of life governed by Justice and the brutality and violence provoked by Injustice. The other pairings, reading from the altar towards the entrance are: Prudence/Folly; Fortitude/Inconstancy; Temperance/Anger; Faith/Idolatry; Charity/Envy; Hope/ Despair.

Sources
The most important literary source for the contrast between the Virtues and Vices, seen as a continuaI struggle within the humansoul, is in the 'Psychomachia' (literally 'battle of the soul') written by Prudentius at the beginning of the fifth century. The text was well known and constantly quoted in Europe throughout the Middle Ages. Prudentius established the con- vention of seven pairs of opposing Virtues and Vices (though occasionally, where even numbered symmetry is required, they may be increased to eight). The antinomies identified by Prudentius are between Faith and ldolatry, Chastity and Lust, Patience and Anger, Humility and Pride, Temperance and Gluttony, Charity and Avarice. Dante himself, in the Purgatory, uses this framework to characterize the journey to Paradise, as the obstacles presented by the seven Deadly Sins - Pride, Envy, Anger, Sloth, Avarice (and Prodigality), Greed and Lust - are overcome with the help of the seven opposing Virtues.

Iconography
The theme of the struggle between virtue and vice had many precedents in medieval art. Giotto's interpretation, however, transforms the spectator's passage between the serried ranks of allegorical figures into a dramatized version of the journey of human existence, bounded by the inescapable obligation to choose one's own destiny. The Virtues are on Christ's right, the side of the blessed, while the Vices, opposite, are on the side of the damned in Hell.
Giotto paints the figures to look like low reliefs against a stone background, but they show a liveliness and expressive freedom which are far from the static quality of sculpture that he is imitating. To make sure they are under- stood, each figure is given an identifying word.