The author addresses, from a psychoanalytical point of view, the issue of the growth of thinking. After a brief outline of Freud's and Melanie Klein's hypotheses in that field, he unfolds the theory of thinking developed by Wilfred Bion, based on the concept of projec­tive identification conceived as a primitive mode of communication between infant and mother : the primitive bodily experiences (beta elements) of the infant are projected on to the mother who has the function to receive and transform theses projections into new ele­ments (alpha elements) that the infant's psyche is able to process. Those elements give meaning to the primitive bodily experiences of the baby. The actual thoughts emerge in his/her mind when the in­fant is able to bear the frustration of the absence of his/her mother. He is now able to extract invariant shapes from his/her previous ex­periences and to apply those invariant shapes to the current situation. In terms of the current scientific models that theory could be interp­reted in terms of emerging properties and structural stability. An ex­tract of the psychoanalysis of a borderline adult patient illustrates that theory and its application to the analytic process.