Analysis of the lead white, performed by the Rijksmuseum, in association with the Free University, Amsterdam used in the painting demonstrates a Dutch or Flemish origin, with a strong possibility that the pigment came from the same batch used for Vermeer's "Diana and Her Companions". The use of a chalk ground is also typically Dutch, and there is an unusually extensive use of ultramarine, typical of Vermeer's later work, though not of "Diana and Her Companions" or "Christ in the House of Martha and Mary". Wheelock identifies stylistic similarities with two history paintings which are universally attributed to Vermeer. He also notes similarities between the depiction of the saint's face and the figure in Vermeer's "A Girl Asleep" and argues that the painter's conversion to Catholicism would have given him an interest in the subject matter. Although it is thought unlikely that the Ferrara painting ever left Italy, or that Vermeer visited Italy, Wheelock points out that he had a reputation as an authority on Italian art. It is possible that another version or copy of the Ferrara painting was the model for Vermeer's work.