战国时期，秦国进攻赵国，包围了赵国的首都邯郸。
情况非常危险，所以赵王派平原君去楚国请求援助。
平原君计划带20个有勇有谋、文武兼备的门客一起去。
平原君说：“如果谈判成功是最好的。如果谈判不成功，那么也要在楚王的宫殿里订立盟约，一定要建立联合对抗秦国的联盟才能回国。我不需要在外面找这样的人才，我的门客中就有合适的人选。”
最后他只选出了19个人，剩下的都不符合要求，无法凑齐20个人。
这时，有一个叫毛遂的人，主动走到平原君面前自我推荐说：“我听说你要去楚国订立联盟，并且打算和20个门客一起去，不需要在外面找人才。现在还少一个人，希望你可以让我充数，和你们一起去。”
平原君问：“你在我这里多久了？”
毛遂回答：“三年了。”
平原君说：“一个真正有才能的人，就像一把放在袋子里的锥子一样，立刻就会露出锋利的尖头。而你在我的门下三年了，我却没有听说过你的表现，你还是留下吧。”
毛遂说：“我现在自我推荐，就是请求你把我放进袋子里，如果早点有这样的机会，那我就不只是露出尖头而已，而是早就显示出了才能。”
平原君觉得毛遂说得有道理，就答应让他一起去。
到了楚国，平原君和楚王会谈，从早上到中午，都没有结果。
毛遂于是拿着剑走到楚王面前，极力说明赵、楚联合对抗秦国的好处。
楚王终于被说服，答应赵国会出兵援救。
于是两国当场歃血为盟，誓守联合对抗秦国的盟约。
毛遂这次不仅帮助平原君完成了任务，也为国家立下了功劳，让大家对他刮目相看，平原君因此待他为上宾。
后来这个故事被浓缩成“毛遂自荐”这个成语，比喻自己主动提出去做某件事。
During the Warring States period, the state of Qin attacked the state of Zhao and surrounded its capital Handan.
The situation was very dangerous, so the King of Zhao sent Pingyuan Jun to ask for help from Chu.
Pingyuan Jun planned to take 20 brave and wise guests who were both literate and martial.
Pingyuan Jun said, "If the negotiation is successful, it would be the best. If not, we must establish an alliance against the state of Qin in the palace of the King of Chu before returning home. I don't need to look for such talents outside, there are suitable candidates among my guests."
In the end, he only selected 19 people, and the rest did not meet the requirements, unable to complete the team of 20.
At this time, a man named Mao Sui walked up to Pingyuan Jun and self-recommended, saying, "I heard that you are going to Chu to establish an alliance and plan to go with 20 guests without looking for talents outside. One person is still needed, and I hope you can let me join and go with you."
Pingyuan Jun asked, "How long have you been here?"
Mao Sui replied, "Three years."
Pingyuan Jun said, "A truly talented person is like a cone in a bag, which will immediately reveal its sharp tip. But you have been under my door for three years, and I have never heard of your performance. You should stay."
Mao Sui said, "Now I am self-recommending, asking you to put me into the bag. If I had such an opportunity earlier, then I would not just reveal the tip, but would have already shown my talent."
Pingyuan Jun thought Mao Sui made sense and agreed to let him go together.
Arriving in Chu, Pingyuan Jun had a talk with the King of Chu, but no results were achieved from morning till noon.
Mao Sui then walked up to the King of Chu with his sword and strongly explained the benefits of the alliance between Zhao and Chu against the state of Qin.
The King of Chu was finally convinced and promised that Chu would send troops to rescue Zhao.
The two countries then made a blood oath on the spot, vowing to abide by the alliance against the state of Qin.
Mao Sui not only helped Pingyuan Jun complete the task this time, but also made contributions to the country, making everyone look at him with admiration. Pingyuan Jun therefore treated him as an honored guest.
Later, this story was condensed into the idiom 'Mao Sui self-recommends',比喻自己主动提出去做某件事。
