A. Theory of the mechanisms of defence. The ego as the seat of observation ; The application of analytic technique to the study of the psychic institutions ; The ego's defensive operations considered as an object of analysis ; The mechanisms of defence ; Orientation of the processes of defence according to the source of anxiety and danger -- B. Examples of the avoidance objective 'pain' and objective danger (Preliminary stages of defence). Denial in phantasy ; Denial in word and act ; Restriction of the ego -- C. Examples of two types of defence. Identification with the aggressor ; A form of altruism -- D. Defence motivated by fear of the strength of the instincts (Illustrated by the phenomena of puberty). The ego and the id at puberty ; Instinctual anxiety during puberty ; Conclusion.