There is another kind of negative trait which, although unaggressive, is only less unpleasant by a matter of degrees than the aggressive ones. It is the black and bitter mood of sullen coldness, of the self-centered, self-tormenting, self-pitying sense of being wronged by the other person, the introverted, withdrawn, sulky, resentment at being hurt, a resentment so deep as to find no fitter expression than gloomy, frozen, and tense silence. He places all the blame for the situation on the other and consequently adopts a grieved unconciliatory attitude towards the other. He wounds by saying nothing, doing nothing, and being boorish. The atmosphere around him is full of sustained and hostile emotional tension. It is, of course, an adolescent trait and cannot endure when spiritual maturity is really attained.
-- Notebooks Category 6: Emotions and Ethics > Chapter 3: Discipline Emotions > # 12