The fourth line of Keeping Still (King Wen 52) is drawn as yin, the numeral six in the old divination manuals. James Legge's translation renders the line as keeping the trunk of the body still, no error. The image sits inside a hexagram whose judgment as a whole concerns resting like the back, so one loses all consciousness of self, walking in one's own courtyard and not seeing the persons in it, no error, and this line supplies one stage of that larger reading rather than a complete statement on its own.
Structurally the line stands at the lowest place of the upper trigram Gen, mountain in Legge's readings of the eight trigrams, while the lower trigram of the hexagram is Gen, mountain in the same traditional set of images. The Great Symbolism of the hexagram reads mountains standing one over another; the superior man does not let his thoughts go beyond his own position, and the fourth line takes its place inside that combined picture of Gen below and Gen above.
Read on its own the line neither opens nor closes the hexagram's argument. It marks the point where Gen is either forming (in the lower trigram) or completing itself (in the upper), and later interpreters treat its image, Keeping the Trunk of the Body Still, as the concrete case through which the hexagram's abstract judgment becomes visible in a single situation rather than a general principle.