The Frisian expressionist Jan Frearks van der Bij belonged, together with Klaas Koopmans and Pier Feddema, to the post-war experimental group 'Yn' e Line '. With the Frisian landscape as the main source of inspiration, these painters sought their own free form language. Van der Bij initially worked in the loose brushstrokes and light colours of Impressionism. The transition to expressionism followed in the early 1950s. The colours became darker, the paint was applied in violent strokes in one big movement. From the 1970s onwards, the painter opted for increasingly brighter colours and a highly simplified design language.