Nine at the beginning means:
The princess of ancient China maintained a fixed order of rank among the court ladies, who were subordinated to the queen as are younger sisters to the eldest. Frequently they came from the family of the queen, who herself led them to her husband.
The meaning is that a girl entering a family with the consent of the wife will not rank outwardly as the equal of the latter but will withdraw modestly into the background. However, if she understands how to fit herself into the pattern of things, her position will be entirely satisfactory, and she will feel sheltered in the love of the husband to whom she bears children. The same meaning is brought out in the relationships between officials. A man may enjoy the personal friendship of a prince and be taken into his confidence. Outwardly this man must keep tactfully in the background behind the official ministers of state, but, although he is hampered by this status, as if he were lame, he can nevertheless accomplish something through the kindliness of his nature.