Such is the intractability of human egoism that if suffering ceases too quickly he learns little or nothing from it. The old habits of thought and patterns of conduct will remain only slightly erased or else not erased at all. If suffering continues too long, it may arouse negative emotions of bitterness, resentment, anger, despair, apathy, or self-pity. Again little or nothing is learned.
-- Notebooks Category 13: Human Experience > Chapter 1: Situation > # 244