A portrait drawing of the Pope by Algardi, in his more customary technique of pen and ink, is in the Academia di San Fernando, Madrid, J. Montagu, Alessandro Algardi, New Haven and London, 1985, I, fig. 172. The present drawing, which was presumably studied from life, recalls Bernini's vivid portrait study of Cardinal Scipione Borghese, also in chalk and with the sitter shown in profile, now in the Pierpont Morgan Library. Although it is impossible to connect the present drawing directly with any of Algardi's busts of the Pope: the rapidly indicated fur trimming and the orphrey are closest to the terracotta bust in the Palazzo Odescalchi, Rome, J. Montagu, op. cit., II, pl. 156