The Cardinal Obligations Continued: Mutual Help
What do all six Cardinal Relations have in common? They all have in common the fundamental feature of human society: mutual help.
Reflecting the fundamental property of human society, the Cardinal Relation between government and subjects is but a relation of mutual help: the government is there to help its subjects by protecting them and keeping order, and in turn the subjects help the government by cooperating with the government so as to make order possible, and by paying taxes to sustain the government.
Also, the Cardinal Relation between parents and offspring is a relationship of mutual help: the parents help the offspring survive, grow up, and learn (become educated). When still immature the offspring help the parents by cooperating with them in the upbringing by obeying and respecting the parents, and when grown up, the offspring help the parents by providing sustenance and care to them in their old age and debility.
The Cardinal Relation between older and younger siblings is a relation of mutual help: the siblings help and cooperate with each other.
As for the Cardinal Relation among spouses, the husband and wife help and cooperate with each other in building a life together.
Of course, mutual help is clearly the real link underlying friendship. Never mind encouraging and admonishing each other, even when it comes to just friends mutually entertaining and amusing each other, that is a form of mutual help.