It was written by Sima Qian. A man's inherent death is more important than Mount Tai or lighter than a feather. This famous saying comes from Sima Qian's reply to his friends in prison, entitled "Report to Ren An", and it is also called "Report to Ren Shao Qing" because Ren An's name is Shao Qing.

The meaning of this sentence is that everyone will die. Some people die more than Mount Tai, while others die less than a feather. The Letter to Ren An was written by Sima Qian in reply to Ren An. Ren An was implicated in prison and sentenced to beheading because he did not obey the prince's orders in the rebellion against the prince's witchcraft.

In prison, he wrote to Sima Qian, hoping that he could intercede with Emperor Wu of the Han Dynasty in the name of "being a scholar". Although Sima Qian was appointed as the official secretary at that time, he was not liked by Emperor Wu, and he was treading on thin ice in officialdom. Although he felt sorry for his friend's experience, he could do nothing about it. He didn't know how to face his friend's help, so he could only write back a letter to him before his execution to express his difficulties and to complete the work of Historical Records.

After the disaster of Li Ling, Sima Qian's mood changed greatly. He no longer dared to speak boldly, but only wanted to save his life and complete the creation of Historical Records. Before Li Ling's disaster, Sima Qian was bent on doing a good job in the post of Taishiling and gaining the trust of the emperor.

However, after he angered the emperor for Li Lingming's injustice, the emperor gave him three choices: redemption with money, execution or corruption. Since Sima Qian had no money and he didn't want to die worthless, he chose castration. Since then, he has only focused on fulfilling his father's wishes and writing Historical Records. Therefore, in order to save his life, he did not speak for Ren An.