The great merchant of the State of Wei, Lu Buwei, went to Handan, the capital of the State of Zhao, to do business, where he encountered Prince Yiren of the State of Qin, who was being held as a hostage there. He considered Yiren a rare "commodity" that could be acquired for a political speculation, to be exchanged for fame and fortune someday.
Returning home, Lu Buwei asked his father, "How many times the profit can a farmer earn from tilling the land in a year?" His father replied, "About ten times." "And from trading in jewels and precious stones?" "Several dozen times." "What if one were to install a ruler as king?" "That," his father said, "would be beyond calculation."
Lü Buwei then brought up the matter of Prince Yiren of Qin, explaining, "I plan to make him the ruler of Qin—a venture that yields ten thousandfold profit with a single investment." His father heartily agreed.
Yiren was the grandson of King Zhaoxiang of Qin and the son of Crown Prince Anguo. Since Anguo favored Lady Huayang and despised Yiren's mother, Lady Xia, Yiren was sent as a hostage to the state of Zhao.
Lü Buwei told Yiren that he was willing to spend money and effort to help him return to the state of Qin; once King Zhaoxiang of Qin passed away and Lord Anguo ascended the throne, Yiren could become the crown prince and eventually succeed as ruler.
The delighted prince repeatedly thanked Lu Buwei, promising that if he ever became ruler of Qin, he would grant half the kingdom to his benefactor.
After the political deal was struck, Lu Buwei traveled to the State of Qin with a fortune in treasures, sending lavish gifts to Lady Huayang through intermediaries. Lady Huayang immediately summoned him. Lu Buwei used his silver tongue to persuade the childless Lady Huayang to adopt Yiren as her own son, then urged her to have Lord Anguo send for Yiren to return to Qin and be renamed Zichu.
From then on, Lady Huayang repeatedly praised Zichu before Lord Anguo, urging him to name Zichu as his heir. Lord Anguo agreed and appointed Lü Buwei as Zichu's tutor.
A few years later, King Zhao of Qin died, and Lord Anguo ascended the throne as King Xiaowen of Qin. Already advanced in age when he took power, King Xiaowen passed away after just one year. As hoped, Zichu succeeded him, becoming King Zhuangxiang of Qin. Lv Buwei, the chief architect of this scheme, was appointed Chancellor and granted the tax revenues of a hundred thousand households. The rare goods he had hoarded were finally traded for immeasurable fame and fortune.
"The Rare Commodity" originally meant hoarding precious goods to sell at a high price later. It refers to stockpiling, monopolizing, or leveraging something—whether an object or skill—to seek fame and fortune in the future. This idiom is used to describe capitalizing on a favorable condition to gain status and profit.
Source: *Records of the Grand Historian*, "Biography of Lu Buwei"
Meaning of the Idiom: Later, the Chinese idiom "奇货可居" came to describe capitalizing on a favorable condition to gain status and profit.