Constant and his partner Matie Domselaer, who would become his wife in 1942, lived along Sarphatipark in Amsterdam during the Second World War. During the war, artists were required to register with the Reich Chamber of Culture to be allowed to continue their practice. Constant did not register and would therefore hide in the crawl space under the house when danger approached. Matie would sit on the hatch to the crawl space and knit away as if nothing was out of the ordinary.