 Just as Erik Erikson was the first analyst to focus on identity and adulthood, Rank was the first to propose that separation from outworn thoughts, feelings and behaviors is the quintessence of psychological growth and development.In the late 1920s, after he left Freud's inner circle, Rank explored how human beings can learn to assert their will within relationships, and advocated a maximum degree of individuation (or "difference") within a maximum degree of connectedness (or "likeness").Human beings need to experience "both" separation and union, without endlessly vacillating between the two poles.