Ancient Greek and Roman coins are obvious sources for Renaissance portrait medals, and Pisanello, among other early Renaissance humanists, is believed to have collected them. The coins typically present the profile portrait of a ruler on one side and an allegorical or symbolic image on the reverse. The tiny silver eagle inset to the left of the portrait of the Roman emperor Galba (no. 1) indicates that the sestertius (a denomination of imperial Roman coinage) belonged to the Gonzaga, who had one of the most significant Renaissance collections.
Another possible source are the medals belonging to Jean de France, the Duke of Berry (nos. 2, 3), which in the early fifteenth century the duke had cast in gold after the gold, mounted, and jeweled discs that bore portraits of Roman emperors. Their size and format anticipate by several decades Pisanello’s medals of contemporary sitters. Seals had been used since antiquity to present an individual’s personal and heraldic devices, and they may also have informed the production of portrait medals. The plaster cast of a later fifteenth-century seal of Charles the Bold (no. 4) was designed by an artist who was also a medalist, demonstrating the association of the two art forms.