As a divinatory line, nine at the fourth place of Small Preponderance reads within the hexagram's overall concern with progress and attainment, but advantage in being firm and correct; small affairs may be undertaken but not great ones, as with a bird flying past that leaves its cry behind, for whom it is not fitting to ascend but only to descend, and there great good fortune. The line occupies a place that does not match its own nature in the classical doctrine that odd places favour a firm, yang line and even places favour a yielding, yin line. Its own text, that no error, meeting the situation without exceeding what is fitting, going forward would be perilous and calls for caution, not to be used long term, is the particular fortune assigned to this one stage of the situation, not to the hexagram as a whole.
The fourth line corresponds by classical convention with the first line, and the two correspond here, since one line is yin and the other yang. Read together with the trigram it belongs to, Zhen in the upper position of the figure, the line marks the first word of the upper trigram, close enough to the ruling fifth line to be shaped by it, 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 fourth line of Small Preponderance turns Zhen into Kun while the other trigram, Gen, stays as it is, which yields Small Preponderance's changing partner, Modesty (King Wen 15), the hexagram this line is recorded as transforming into.