For topographical purposes, use a whole page to represent the self. Put a round hole in the middle to represent the outside world. The ego defences are clustered round the edges of
the hole.
Perhaps the most typical defence mechanism is rationalisation, which actually operates unconsciously. It aims to categorise the outside world and thereby eliminate grey areas.
Grey areas are a major threat to the organism. They make it impossible for it to calculate probabilities or to select which stimuli to respond to or to ignore.
This defence mechanism needs to be suspended periodically in order to revise the categories and admit ambiguous areas which have previously been excluded.