东汉时，杨震曾推举秀才王密，四次升官。杨震路过昌邑县，原先他所推荐的秀才王密，此时已是昌邑县令，夜里怀中揣着十斤金子来赠送给杨震。杨震说：“作为老朋友，我了解你的为人，你却不了解老朋友我的为人，这是为什么呢？王密说：“夜里没有人知道。” 杨震说：“天知，地知，我知，你知。你怎么可以说没有人知道呢？”王密愧疚地出门走了。

In the Eastern Han Dynasty, Yang Zhen once promoted the scholar Wang Mi, who was promoted four times and became the top magistrate of Changyi County. Once when Yang Zhen stayed in Changyi County, Wang Mi presented Yang Zhen with ten jin (a unit of weight, one jin equals half kilogram) of gold in his arms at night. Yang Zhen said, “As old friends, why I know you so much, but you don’t know me at all?” Wang Mi said, “No one knows that at night.” Yang Zhen said, “God knows, and earth knows. I know and you know. How dare you say that no one knows?” Hearing about this, Wang Mi went out with guilt.