According to the
Netherlands Institute for Art History, he was named after his house on the Amsterdam Koningstraat, which was called "De Duystere Werelt", the
dim world. He knew his exact contemporary
Pieter Codde well though, in a brawl between them in 1625, Codde hit him in the face with a "tin pitcher" at a country house party hosted by another artist. He married the sister of the painter
Simon Kick (1603–1652), who in turn married Willem's sister. ==Painting career==