He once wrote a letter to his friend Ren An，and told him about how he had been wronged and put in prison。He stated that from ancient times，every one had a natural death，but some were lighter than a feather and some heavier than Mount Tai。People died in different ways and so they have different meanings。
“I don't want my death to be like a feather and be looked down upon。I am quite unhappy for having received the worst punishment。Like a tiger being put in a cage-the King of Beasts may have to wag his tail and beg for food。But being a man，I should draw a circle to serve for me as a prison：Bearing the insult and live among the unworthy，to fulfill my late father's great will。I must finish the historical book for the later generations，and put it in a famous mountain and then die a worthy death。
Sima Qian was referring to the idiom“to Make a Prison by Drawing a Circle on the Ground”。In ancient times，a circle meant a prison in which pri-soners were kept。Later it became an idiom，which means someone's confined to a little place。