One of Freud's main contributions to psychoanalysis is that he believes dreams have a meaning. Freud based his understanding of dreams on his work with neurotic patients and suggested that the symptom or the dream represents both the expression and disguise of an unconscious wish. While Freud built the psychoanalytic structure on dreams, his primary interest consisted in the field of dream interpretation. Psychoanalytic meaning of the dream can be revealed by using free associations applied to the parts of the dream, not only to the dream as a whole. Freud uses the puzzle analogy for the interpretation of dreams and states that if one succeeds in arranging the confused heap of fragments, each of which bears upon it an unintelligible piece of drawing, the picture acquires a meaning. The path to the meaning of the dream is a way to invent the psychic object.