A preparatory study for the pendentive Justice, Peace and Truth in Sant'Agnese, Rome painted around 1666 to 1672, R. Enggass, The Paintings of Baciccio, Giovanni Battista Gaulli 1639-1709, Pennsylvania, 1964, fig. 16. Sant'Agnese was the church of the Pamphili and they asked Bernini who had designed for them the Fountain of the Four Rivers in the Piazza outside, to recommend an artist for the pendentives. He recommended the young Baciccio and introduced him to Principe Pamphili. The commission was the largest and most prestigious he had ever received, and the lengthy preparatory process reflects both the importance of the project and the fact that he had probably never before worked in fresco. Part of his preparation was a visit to Parma in 1669 to study the frescoes of Correggio. The present drawing may date from after his return, as the upraised arm and the foreshortened upturned face of Truth recalls Correggio's figures such as Eve in the Duomo, Parma.

The drawing differs from the fresco in a number of ways but the general arrangement of Peace whispering to Justice, with a figure pointing to the Decalogue below, remains virtually unchanged. Equally the pose of the putto crowning Justice, a virtuoso display of foreshortening, is almost the same in the fresco although he is moved to the left. A preparatory drawing closer to the final composition is at Windsor, A. Blunt and H.L. Cooke, The Roman Drawings of the XVII & XVIII Centuries in the Collection of Her Majesty the Queen at Windsor Castle, London, 1960, no. 146, pl.48