To summarize this contribution I would say this: to achieve the optimal reconciliation between ego and id the patient in treatment has to become acquainted with those defence mechanisms which he employed when fighting his conflicts of childhood, and the anxieties arising from them. To reach these defences the hierarchical structure of the defensive organization may become a help or an obstacle. It will be a help when it is considered and handled as the necessary and constructive concomitant of the search backwards into the childhood history: it will be an obstacle when the analyst loses sight of the historical and developmental aspect of the defensive organization and treats it indiscriminately as if it were itself a pathological formation.