During the final years of the Zhou Dynasty, after King Jing of Zhou ascended the throne, eager to amass greater wealth for his own pleasure, he decreed the abolition of the small coins then in circulation and ordered the minting of a new, larger currency.
Grand Councilor Shan Mugong admonished, "Your Majesty, abolishing small coins and minting large ones will harm the common people. If the people are impoverished, the state cannot be governed!"
However, King Jing of Zhou ignored the advice and continued as he pleased, amassing a vast fortune by plundering his people.
Two years later, seeking personal pleasure, he ordered all the finest bronze in the kingdom to be gathered and cast into two massive bells.
Shan Mugong advised again, "Your Majesty, two years ago you cast large coins and abolished small ones, causing great losses to the people. Now you want to build a large bell. This not only exhausts the people and wastes resources, but using a large bell for music will also produce disharmonious sounds."
King Jing of Zhou, ignoring all advice, ordered the casting to continue. A year later, two massive bells were completed—one named "Wuyi" and the other "Dashen." A flattering bell-ringer, eager to curry favor, said, "Your Majesty, the new bells produce the most exquisite sound." The king then commanded him to strike them. After listening, King Jing turned to his music official, Zhou Jiu, and said, "Do you hear how harmonious the bells sound?"
Zhou Jiu, who understood the suffering King Jing's bell-casting had inflicted on the people, replied, "This cannot be called harmony. If Your Majesty cast a bell and all the people rejoiced, that would be true harmony. But you have exhausted the people's wealth and drained their resources to make this bell, and everyone resents it—so I fail to see what is good about it. As the saying goes, 'A united will can move mountains; public opinion can melt gold.' When everyone is of one mind, anything can be accomplished; conversely, if all oppose something, even gold can be dissolved by their words."
Later, the idiom "unity is strength" came to be used to describe how when many people work together with one heart, success is certain.
Source: *Guoyu*, "Discourses of Zhou"
Meaning of the Idiom: Later, the Chinese idiom "众志成城" came to describe how when many people work together with one heart, success is certain.