As a divinatory line, nine at the fifth place of Development reads within the hexagram's overall concern with the marriage of a young lady, and the good fortune attending it, advantage in being firm and correct. The line occupies a place proper to its own nature in the classical doctrine that odd places favour a firm, yang line and even places favour a yielding, yin line. It is also one of the two central lines of the hexagram, the place classical reading treats as the most balanced regardless of the line's own character. Its own text, that the geese gradually advancing to a high mound, a wife who for three years does not conceive, but in the end nothing can prevent what is natural, good fortune, is the particular fortune assigned to this one stage of the situation, not to the hexagram as a whole.
The fifth line corresponds by classical convention with the second line, and the two correspond here, since one line is yin and the other yang. Read together with the trigram it belongs to, Xun in the upper position of the figure, the line marks the ruling stage of the hexagram, the place classical reading treats as its centre of authority, one stage in the six stage movement the hexagram traces from its first line to its last.
A change at this line, from yang to its opposite, is the mechanism the tradition uses to move from one hexagram to another. Flipping the fifth line of Development turns Xun into Gen while the other trigram, Gen, stays as it is, which yields Development's changing partner, Keeping Still (King Wen 52), the hexagram this line is recorded as transforming into.