Anyone in the 17th century who knew their classics would have recognised this naked man. It is the muscular Roman demigod Hercules, with his singular lion-skin and club. Goltzius was commissioned to paint Hercules’ defeat of the giant Cacus by a Haarlem lawyer, Johan Colterman, who also bought his Minerva and Mercury. Colterman’s son apparently posed for the painting, which explains a lot. Because Hercules’ body is rather ordinary – this is no superman, but a mere mortal