《宋史·列传·卷十五》
赵普说： 太原地当西、北二面，太原如果攻下，则我国须单独抵挡这两面，不如等削平诸国以后，则太原这一弹丸黑子之地，能够哪里逃得掉呢？ 皇帝笑着说： 我的意思正是这样，特地来试试你罢了。 
普曰 太原当西北二面，太原既下，则我独当之，不如姑俟削平诸国，则弹丸黑子之地，将安逃乎？ 帝笑曰： 吾意正如此，特试卿尔。 
Zhao Pu said: Taiyuan is very close to the west and the north. If Taiyuan is conquered, then our country will have to resist these two sides alone. It's better to wait until all the other nations are conquered, then where can a small place like Taiyuan escape to? The emperor laughed and said: This is exactly what I mean, I came here just to test you.