A space is divided into 4 rooms by 2 walls. A Euclidean space moving like the XY axis of a plotter. The 4 rooms are constantly changing in size, when one becomes larger another becomes smaller. However the walls are nearly immaterial: the plan of the walls is only indicated by vertical strings hanging down. Together with light and shadow they may look like a sterile autocad drawing or a projection. Yet when a string touched a visitor it curves and hesitates like only physical objects can.