The Collected Works of William Hazlitt

Man is the only animal that laughs and weeps; for he is the only animal that is struck with the difference between what things are; and what they ought to be. We weep at what thwarts or exceeds our desires in serious matters: we laugh at what only disappoints our expectations in trifles. We shed tears from sympathy with real and necessary distress; as we burst into laughter from want of sympathy with that which is unreasonable and unnecessary; the absurdity of which provokes our spleen or mirth; rather than any serious reflections on it.