《资治通鉴·汉纪·汉纪三十三》
到了汉成帝时，把皇帝的威严让给外戚。以后汉哀帝、汉平帝在位时间都很短，皇位的合法继承人三次断绝。所以王莽专擅朝政，得以篡夺皇位。国家的危机来自最上层，没有伤害到百姓。所以王莽篡夺皇位成为事实以后，天下人无不伸长脖子叹息。
至于成帝，假借外家，哀、平短祚，国嗣三绝，故王氏擅朝，因窃号位，危自上起，伤不及下，是以即真之后，天下莫不引领而叹。
In the time of emperor Cheng, the emperor's authority was given to his maternal relatives. Later, emperor Ai and emperor Ping's reign were very short, the legal emperor's successors were broken three times. That was why Wang Mang controlled the government and could usurp the throne. The crisis of the country came from the top, not hurt common people. So after Wang Mang usurped the throne, people sighed with sympathy.