《魏书·列传·卷五十》
其实是从政的人必须循序渐进，而受教化的人难以一下子幡然顿悟的缘故，如今若立制度以区别品级，始末之情，魏人与郑人也会一样。
且从政者须渐，受化者难顿故也。今若为制以差品之，始末之情，魏士与郑人同矣。
Actually, it is because the people who govern the country need to take gradual approaches while the people who are educated find it difficult to suddenly realize the truth overnight. Nowadays, if we make a system to distinguish grades, the people of Wei will become the same as the people of Zheng at the end of the day.