The pursuit of union, a pervasive theme in human psychology, is examined from the adaptational point of view by relating it to both oral and genital intimacy. The extreme dependency of the infant creates, through separation anxiety and consequent strivings for fusion, a lifelong threat to autonomy, and generates diverse searches for blissful union, which share a mystical character and a fear of annihilation derived from fantasies seeking to reconstruct preverbal experiences.

Development of the capacity for a mature heterosexual relationship (i.e., achievement of a genital object representation) constitutes the most valuable protection from this threat to autonomy. The actual enjoyment of such a relationship continuously refines,