任安

Ren An had once urged Sima Qian to recommend able men to the court. Sima Qian answered him years later, when Ren An was in prison under sentence of death after the crown prince's revolt of 91 BC. In 《报任安书》 he explains why he chose castration over death: 人固有一死, and some deaths weigh more than Mount Tai, others less than a feather.

His courtesy name was 少卿, so the same letter is also called 《报任少卿书》. As a surname 任 is read Rén, not rèn.