《资治通鉴·汉纪·汉纪三十三》
事情没有发生时的预言，原本常被认为是虚幻。等到事情已经发生，又什么都来不及了。
夫未至豫言，固常为虚；及其已至，又无所及。
Prophecies that are made before events happen are often regarded as unreal. When events have already happened, it is too late for everything.