Sentence:  This is the precise point of either the "optimal frustration" that Spitz requires of the mother towards the child, or of Winnicott's mysterious  "good enough mother": they are called upon to break the primary narcissism in which the mother and child are bound, from anaclisis to <WSD>diatropism</WSD>, so that, with the advent of autoeroticism, and at the same time as representation and language, a relationship of the object is finally begun. 
Meaning of the word marked with <WSD> tags:  The choice of an object of libidinal attachment on the basis of dissimilarity from early childhood protective and parental figures.