鱼目混珠 — “To pass off a fake as genuine”

Once upon a time, a man named Manyi spent all his money on a large pearl from an inconspicuous shop in a desolate place. Returning home, he placed the pearl in a specially crafted box, preserving it carefully, only showing it to friends during the New Year.

Manyi had a neighbor named Shouliang, who possessed a large ancestral pearl and often wished to compare it with Manyi's. However, his ancestors had forbidden showing it easily, so he refrained.

Before long, both men contracted a strange illness, confining them to bed. Despite consulting many doctors and taking various medicines, their condition did not improve. One day, a wandering doctor, reputed to cure various difficult diseases, arrived in the street. Both families invited him home.

After examining them, the doctor stated that pearl powder mixed with other herbs was necessary for a complete cure. He left a prescription and hurried away. Manyi, however, couldn't bear to damage his rare pearl, so he only took the other medicines. Shouliang, on the other hand, consumed the medicine mixed with his family's ancestral pearl powder.

Later, when the doctor learned Manyi had not used the pearl powder, he visited and confirmed Manyi's pearl was indeed a rare treasure. Upon seeing Shouliang's 'pearl', the doctor exclaimed, "This is the eye of a large ocean fish, passing off a fish eye as a pearl. How could it possibly cure your illness?"