The country of Lu 鲁国 was a small country of the Warring States era, and had a priceless censor. Its larger neighbor’s king demanded it as a tribute. The Lu king did not wish to give up the national treasure, and therefore had a fake censor made and intended to present it as the original.
The sovereign ruler said, “If his adviser Nhạc Chính Tử 樂正子 (Zeng Zi’s famous disciple) brought it here himself, only then would I believe that it is genuine.”
The King of Lu asked Nhạc Chính Tử to bring the fake censor to the sovereign king.