"A swan fiercely defends its nest against a dog. In later centuries this scuffle was interpreted as a political allegory: the white swan was thought to symbolize the Dutch statesman Johan de Witt (assassinated in 1672) protecting the country from its enemies. This was the meaning attached to the painting when it became the very first acquisition to enter the Nationale Kunstgalerij (the forerunner of the Rijksmuseum) in 1880." https://www.rijksmuseum.nl/en/collection/SK-A-4