《贞观政要·卷三·论封建》
周朝借鉴夏殷统治长久的经验，遵循前代的统治经验，实行皇帝与诸侯并存的制度，加强统治力量，注意保全根本，即使王道废弛，可是各个朝代统治祭祀却没有断绝。
周氏以鉴夏、殷之长久，遵皇王之并建，维城磐石，深根固本，虽王纲弛废，而枝干相持，故使逆节不生，宗祀不绝。
The Zhou Dynasty learned from the long-term ruling experience of Xia and Yin, followed the ruling experience of the previous generations, implemented the system of coexistence between the emperor and the vassal states, strengthened the ruling power, paid attention to preserving the foundation, and although the king's way was abolished, the ruling sacrifices of each dynasty did not did not cease to exist.