The progressing disciple who reaches an advanced state will find that his powers of mind and will develop accordingly. Where they are not accompanied by sufficient self-purification, they may become dangerous to himself and hurtful to others. His vigilance over thought and feeling must become greater accordingly. To dwell upon thoughts which belong to a lower level out of which he has climbed may open up a pitfall in his path; to hold bitter feelings against another person may throw discord into that person's life.
-- Notebooks Category 6: Emotions and Ethics > Chapter 1: Uplift Character > # 181