The mechanism of projective identification enables the infant to deal with primitive emotion and so contributes to the development of thoughts. The interplay between the depressive and paranoid-schizoid positions is also related to the development of thoughts and thinking. It has been pointed out that symbol formation is related to the depressive position. The earliest observation, the author has been able to make seemed to suggest that development of thinking through Ps ↔ D depended on the production of signs. That is to say the individual had to bring together elements to form signs and then bring signs together before he could think. The procedure, the author have just described qualifies as an attempt to establish thought, because although the verbalizations seemed to refer to the objects present, scrutiny showed that the objects were being used as signs to make thinking possible about objects that were not present.