Bernini’s relationship with clay modeling has always been very intense: the artist works with rapidity and freshness on the malleable material to obtain a series of even more varied and vibrating effects compared to the surprising results achieved on the marble surface. However, precisely this sphere of his production, of which we know from the sources the conspicuous entity, presents areas of shadow and still open questions, on which the recent exhibition in New York (2013) has tried to throw new light, highlighting, at the same time, the intrinsic difficulties associated with this type of material. The discovery of a new version of the model for the figure of San Girolamo destined for the Chigi chapel in the Cathedral of Siena therefore offers an opportunity to reflect on the nature and the possible function of some of these artifacts not without evading the thorny problem of the autography often uncertain and that of Bernini only maintains the idea.