In the hexagram of the Army, Nine in the Second Place is the sole yang line to which all yin lines turn. The fifth line occupies the ruler's throne and is its proper correlate; the second line is the master of the army, holding sole executive authority over its affairs.
Residing below yet wielding undivided command can only be permissible in military matters. From antiquity, when appointing a general, matters outside the borders have been left to his sole discretion.
Exercising sole authority in the army while maintaining the Central Position brings good fortune and freedom from blame. If one arrogantly relies on sole command, one loses the virtue of a subordinate; if one does not take sole authority, there is no way to achieve success.
Thus, attaining the middle is auspicious. In the art of warfare, when both majesty and harmony prevail, good fortune follows. Handling affairs with complete virtue enables one to achieve success and bring peace to the world; therefore, the king bestows thrice-repeated honors.
In all things, reaching three represents the ultimate. Six in the Fifth Place above trusts him wholeheartedly and heaps generous honors upon him; for if rites do not match the post, authority will not be weighty and subordinates will not place their trust.
In other hexagrams, there are cases where Nine in the Second Place is employed by Six in the Fifth Place; only in the Army does it hold exclusive mastery over affairs while uniting all yin lines beneath it, making its significance the greatest.
In the way of a minister, one dares not monopolize authority in ordinary affairs; only beyond the gates of the capital may one take exclusive command.
Although the command rests in oneself, the results achieved through the army's power are entirely bestowed by the sovereign and are what one's duty requires.
Later scholars argued that Lu's sacrifice to the Duke of Zhou with imperial rites and music was justified because the Duke had achieved merit beyond what ordinary ministers could accomplish, and could thus use rites ordinary ministers could not use—this shows ignorance of the minister's way.
Occupying the post of the Duke of Zhou, one performs the duties of the Duke of Zhou; whatever one can achieve by virtue of one's station is merely what one ought to do. The Duke of Zhou merely fulfilled his duty.
The same applies to the way of filial piety; only Mencius understood this when he said, 'Serving one's parents like Zengzi is sufficient,' never considering Zengzi's filial piety to be excessive, for whatever a son can do in his person is simply his duty.