Mental states described as blankness, or by such phrases as 'There is nothing in my mind', may be investigated by requesting the subject to describe the experience. Often this will arouse memories or associations which indicate that these states contain visual memories which have lost their outlines and distinctness. The memory has become a homogeneous part of the perceptual field. Many of the memories are of the maternal breast. Others are memories of later screens which have served to prevent the child from carrying out some action or satisfying some curiosity. They function as barriers between what is conscious and what is unconscious, and therefore serve the forces leading to repression. They continue to function internally as they once functioned externally, to exclude painful feelings and thoughts from consciousness.