Nine at the beginning means:
The family must form a well-defined unit within which each member knows his place. From the beginning each child must be accustomed to firmly established rules of order, before ever its will is directed to other things. If we begin too late to enforce order, when the will of the child has already been overindulged, the whims and passions, grown stronger with the years, offer resistance and give cause for remorse. If we insist on order from the outset, occasions for remorse may arise-in general social life these are unavoidable-but the remorse always disappears again, and everything rights itself. For there is nothing easily avoided and more difficult to carry through than "breaking a child's will."