"Mr. Yin of Chou runs a big business and keeps his servants working all day long unmercifully. There is one old servant in particular whose physical strength has quite left him, yet Mr. Yin makes him work even harder. All day long the old man keeps groaning as he goes about his work, and when night comes he is reeling with fatigue and will sleep like a log. His spirit is then set free to adrift at will, and every night he dreams that he is a king in authority for all people, and controlling the affairs of the whole country. He takes his pleasure in palaces, with indulgence in comfort and joy to his heart's contents. But when he awake, he is the old servant again. To someone who condoles on his hardship the old man replys: 'Human life may last a hundred years, and the whole of it is equally divided into nights and days. In the daytime I am only a slave -- how much I suffer! But by night I am a king, and my happiness is beyond compare. So what do I have to grumble at?'
Now, Mr. Yin's mind is full of worldly cares and racks his brains with towering anxiety for the affairs of his estate. He is overworking himself in both mind and body, and at night he also falls asleep utterly exhausted. Every night, however, he dreams that he is another man's servant, running about on others' menial business; and falls prey only to abuse and ill-treatment. He will whine and groan in his bed, only to find relief until morning came. This state of things at last costs him serious illness, and Mr Yin seeks the advice of a friend about the affliction. 'Your station in life,' his friend said, 'is glorious and your wealth is inexhaustible. You have well passed others in these respects, so it is natural for you to see yourself in dreams as a slave, for where can you find a person so lucky that he finds pleasure in both reality and in dream?' On hearing what his friend said, Mr Yin lightens his servant's toil, and allows his own mental worry to abate. In this way, pains of both parties begins to decrease in proportion." "Lieh Tzu -- Book III Dreams"