M. Leithe-Jasper and P. Wengraf, European Bronzes from the Quentin Collection, exh. cat., The Frick Collection, New York, 2004, no. 17.
It remains unclear who these dramatic busts represent. It has been suggested they either represent philosophers or the figures of Mars and Vulcan. Many of the facial feature and expressions do relate them closely to the Mars and Vulcan by Bandini from the Quentin Collection.
There are three other known versions of these busts. A larger pair was sold Christie's London, 9 December 2004, lot 189. A virtually identical pair is in the Hermitage Museum, St. Petersburg and is listed in an 1859 inventory of the sculpture as 'French, 17th century'. And there is a third, smaller pair that was sold at Christie's London, 15 July, 1986, lot 53. While the present pair is not this pair -- they do not have the visible punched holes in the breastbones -- they do appear to be the same model as they are exactly the same size and appear to be the same in all the modelling details.