《北史·列传·卷二十四》
薛道衡说： 凡讨论大事的成败，必须先用牢不可破的道理去判断。
君试言之。 道衡答曰： 凡论大事成败，先须以至理断之。
Hsiao Tao-heng said: "In order to deliberate on the successful outcome of any great undertaking, it is imperative first to base one's judgment on an inviolable principle."