Nine in the second place, as a changing line, describes the discipline required to keep an established peace genuinely open rather than letting it settle into narrowness. A querent shown this line is asked to bear with what is unrefined, to act boldly where the situation demands it even without conventional support, to keep the distant in mind rather than only the near, and to set aside factional loyalty in favor of a wider, more central course.
Flipping this line changes the lower trigram from Qian to Li, Fire, giving Kun over Li, the hexagram called Darkening of the Light. The broad, inclusive balance the second line describes gives way, on the far side of change, to a hexagram of brightness concealed beneath the earth, virtue that must hide itself rather than act openly. The movement is striking, the very line that shows peace kept open through breadth and impartiality is the one whose transformation produces a hexagram where that same light can no longer show itself safely at all.
Within Peace's arc, the second line is where an established harmony is actively maintained rather than merely inherited from the first line's rising momentum, and its centrality is the resource that maintenance draws on. A reading landing here suggests present stability depends on continuing exactly this kind of broad, unfactional conduct, and that abandoning it risks the very concealment the transformation names.