To investigate the relation of the primary and the secondary system, Ramsey (1929a, [FM] 215–19) provides a primary system for an agent who, in discrete time intervals, can move forwards and backwards, open and close their eyes, and see blue, red, or nothing. In the secondary system, Ramsey formulates a toy theory that describes the movement of the agent among three locations and the sometimes changing color of the locations. A dictionary defines the primary terms in the secondary system so that, for instance, the agent sees blue if and only if situated at a blue location with open eyes.