Yin & Yang Lines

Yin and yang lines are the units of a hexagram. They identify contrasting forms whose positions and combinations supply context. Yin is not a bad rating and yang not a good one. Textual Six/Nine headings, four casting values and six line positions are related but distinct notations.

Yang is solid and yin broken. Positions run upward from initial through second, third, fourth and fifth to top. Received headings use Nine for yang and Six for yin, as in Initial Nine, Six in the Second, Nine in the Fifth and Top Six.

Casting gives 6 Old Yin, 7 Young Yang, 8 Young Yin and 9 Old Yang; 6 and 9 move, 7 and 8 stay. A first-line 7 is stable Young Yang but its textual heading is Initial Nine. A third-line 8 is stable Young Yin but its heading is Six in the Third. Draw polarity first, then use actual movement to construct changes.

Textual readings distinguish correct placement and centrality. Positions 1/3/5 are conventionally yang and 2/4/6 yin; matching polarity is correct placement. Lines two and five are central in the lower and upper trigrams. Nine in the Second is not polarity-matched but is central; Six in the Fifth is also central without matching polarity.

These are positional concepts. Najia strength instead examines branch elements and calendar relationships. Nine in the Second does not by itself mean a moving Old Yang line, and positional fit is not a substitute for element strength.