In this painting, Saint Jerome Writting, The arms in the bottom right-hand corner on the post are those of Ippolito Malaspina, Prior of the Order of the Knights of St. John in Naples and probably the man responsible for introducing Caravaggio to Malta. Certain writers have drawn attention to the facial resemblance between St. Jerome and Alof de Wignacourt, but the similarity is not striking enough to suggest that Wignacourt was actually used as a model.
The composition, however, shows that Caravaggio was here thinking in terms of a solution similar to that which he devised for The Beheading of St. John the Baptist. A subtle diagonal, implying movement, leads across the composition only to be held in check by the emphatic vertical which marks its juncture with the picture plane. Unlike certain earlier works such as The Conversion of Saul, asymmetry and diagonal rhythm in St. Jerome are fully contained within the space of the picture. They help to lead the eye into the picture, but no longer threaten to invade the physical and psychological territory of the viewer. The distancing effect thereby achieved has more in common with the: values of classicism than it does with the rhetorical exuberance of much Baroque art. The picture was until recently in the Co-Cathedral's chapel of St. Catherine, which belonged to the Italian 'Langue' of the Order.