《贞观政要·卷三·君臣鉴戒》
贞观十七年，唐太宗对侍从的大臣们说： 从古以来开创基业的君主，到他子孙手里往往发生祸乱，这是什么缘故？ 
贞观十七年，太宗谓侍臣曰： 自古草创之主，至于子孙多乱，何也？ 
In the 17th year of Zhenguan, Emperor Taizong said to the attendant ministers: Since ancient times, the monarchs who founded the foundation often had troubles in their children and grandchildren's hands. What is the reason for this?