Mozi, known as Mo Di, was the founder of the Mohist school during the Spring and Autumn period, whose main doctrine was opposition to warfare.
Mo Di, also known as Mozi, once served as a high official in the State of Song and traveled to many feudal states, successfully mediating several wars between them. He established a large private school with a devoted group of disciples who were fiercely loyal to Mohist teachings, willing to brave any danger—even fire and boiling water—to realize their ideals.
Once, Mo Di was traveling to the northern state of Qi. On the way, he met a man named Yue, who said, "Sir, you must not go further north. Today the Heavenly Emperor killed a black dragon in the north, and your skin is dark—going north is very dangerous!"
Not believing his words, Mozi continued northward, but soon returned—to reach Qi he had to cross the Zi River, yet the river was flooding and impossible to cross.
When "Yue" met Mozi, he smugly said, "See? I told you the north was dangerous and not to go there, but you wouldn't listen. Now you've hit a wall and come back!" Mozi smiled faintly and replied, "The Zi River in the north flooded, preventing everyone from crossing—both dark-faced and fair-faced people alike. It wasn't just the dark-faced ones who couldn't get through!" Left speechless, "Yue" had no retort. Mozi continued,
“If the Heavenly Emperor killed the Azure Dragon in the east, the Vermilion Dragon in the south, the White Dragon in the west, and the Yellow Dragon in the center,” the man argued, “then wouldn’t everyone be trapped at home, unable to leave? So your lie is as fragile as an egg thrown against a rock—smash every egg in the world, and the rock remains unbroken forever.”
After hearing this, he left in shame. Later, the idiom "throwing an egg against a rock" came to describe overestimating one's strength and courting destruction.
Source: *Mozi*, Chapter "Valuing Righteousness"
Meaning of the Idiom: Later, the Chinese idiom "以卵击石" came to describe how overestimating one's strength and courting destruction.