To emphasize the necessity of acting in accordance with objective principles and verified facts, rather than relying on superficial observations or assumptions.
在项目规划中，我们必须遵循黑牛白角的原则，充分调研市场需求和技术可行性，才能确保成功。
In project planning, we must adhere to the principle of 'black cow, white horns,' thoroughly investigating market demands and technical feasibility to ensure success.
Era:
Ancient
Frequency:
Story:
In ancient times, Zhan He was lecturing at home, with his disciples attending him.
The sound of a cow bellowing came from outside the gate.
One disciple guessed it was a black cow with a white forehead.
Zhan He, using his Taoist arts, acknowledged it was a black cow but said the white part was on its horns.
He sent someone to verify, and it turned out to be a black cow with a piece of white cloth wrapped around its horns.
Next Idiom