In a study of 1984 I proposed that Antonello da Messina’s Saint Jerome in his Study in London portrays Nicholas of Cusa in the guise of Saint Jerome. Returning to this identification I first discuss certain objections against it, which concern the dating of the painting and the question whether a contemporary person is represented. In the subsequent sections I expand my findings in the past with recent ones, focusing on: the similarities between Antonello’s figure and Cusanus’s portrayal on his funerary monument in San Pietro in Vincoli in Rome and in one of Pinturicchio’s frescoes in the Libreria Piccolomini in Siena; Cusanus’s connection, as explicitly expressed in his will, with Saint Jerome, patron saint of the monks who were active in San Pietro in Vincoli; the relation of iconographic motifs in the painting with a manuscript in his possession and with Konrad von Megenberg’s Das Buch der Natur, which he, as a German scholar, interested in natural history, may very well have known; and the meaning of the iconographic programme in light of his function as legatus urbis, when, during the congress of Mantua, he represented Pius II in Rome. I also argue that, while Cusanus was responsible for its programme, Pius II ordered the painting as a gift to him, for which the Saint Jerome in his Study by Jan van Eyck or his workshop, in Detroit, representing Niccolò Albergati in the guise of Saint Jerome, was a source of inspiration. Antonello’s panel in its turn must have inspired Albrecht of Brandenburg, who seems to have regarded Cusanus as a role model, to order paintings by Cranach that portray him in the guise of Saint Jerome.