《列子·周穆王》
有人安慰他过于勤苦，老役夫说： 人一生活一百年，白天与黑夜各有一半。
人有慰喻其懃者，役夫曰： 人生百年，昼夜各分。
Someone tried to comfort him and said that he was working too hard. The old man replied: When a man lives to be a hundred, half of his time is spent awake, and the other half asleep.