Hissing furiously, her wings outstretched to their fullest extent, this impressive swan defends her nest from an approaching dog. Feathers swirling in the air and the water dripping from the swan’s webbed feet create the impression that the creature has only just managed to reach dry land, having been caught completely off guard by the sudden peril. The enraged bird is depicted over life-sized and appears almost poised to fly right out of the painting. But what makes The Threatened Swan even more remarkable is the presence of inscriptions, added after the death of the painter, Jan Asselijn. No comparable animal painting is known with inscriptions that have raised so many questions. Many other details surrounding this seventeenth-century painting are still cloaked in mystery. Who commissioned the work? Why did Jan Asselijn depart from his customary themes to produce a painting of a bird on such a large scale? Was it based on a fable, and if so, which? How did the work end up in the collection of the Rijksmuseum?