Changing lines in an I Ching consultation indicate where the hexagram is alive and in motion, where the pattern of the moment is under pressure to transform. They mark the points at which yin becomes yang or yang becomes yin, revealing areas of instability, dynamic potential, and active forces at work. In this sense, they do not merely decorate the hexagram; they show where attention is most needed, where decisions and attitudes will have the greatest impact, and where the situation is most susceptible to change.

Each changing line carries its own specific text and commentary, which refines and qualifies the broader meaning of the hexagram as a whole. These line texts offer concrete guidance about particular aspects of the situation: attitudes to adopt or avoid, mistakes to recognize, opportunities to cultivate, and stages in the unfolding process. Because of this, the changing lines often provide more pointed and practical counsel than the general judgment of the hexagram, functioning as a kind of inner commentary on how the larger pattern is actually playing out.

When lines change, they generate a second, related hexagram by transforming the affected lines into their opposites. The original hexagram portrays the present configuration of forces, the prevailing pattern of the situation as it now stands. The resulting hexagram shows the direction of movement, the likely development of events, or the deeper pattern that is emerging through the changes indicated by the moving lines. Together, original and resulting hexagrams, read through the lens of the changing lines, offer a picture of both present circumstances and their natural evolution.

The number and placement of changing lines further color the reading. A single changing line often points to a clear, central issue, while multiple changing lines suggest a more complex and turbulent field of transformation, with several factors in motion at once. Readers may treat these multiple lines as indicating degrees of intensity or as a progression through different stages of change. In all cases, changing lines serve as the focal points through which the I Ching reveals how a situation is shifting and how one might align more skillfully with that movement.