For man never reasons so much and becomes so introspective as when he suffers ; since he is anxious to get at the cause of his sufferings, to learn who has produced them, and whether it is just or unjust that he should have to bear them. On the other hand, when he is happy, he takes his happiness as it comes and doesn't analyse it, just as if happiness were his right.
Luigi Pirandello, Six Characters in Search of an Author
happiness, ingratitude, sadness