Influence is human movement, which is why the images are drawn from the human body. The toe is taken for being at the bottom and representing subtle movement; the calf is taken for moving first; the thigh is taken for following along.
Nine in the Fourth Place takes no specific bodily part, but speaks directly of the Way of influence, not saying 'influence in the heart,' because influence itself is the heart.
The fourth line is central and situated above, occupying the position of the heart; therefore it is the lord of influence, and speaks of the Way of influence.
If it is correct and steadfast, there will be good fortune and remorse will vanish; if it influences without correctness, there will be remorse.
Furthermore, the fourth line is of the joyous trigram body, occupies a yin position, and responds to the initial line; hence it is warned regarding steadfastness.
The Way of influence penetrates everywhere; if there are selfish attachments, they obstruct mutual resonance and penetration, resulting in remorse.
When the sage influences the hearts of all under heaven, it is like the cold, heat, rain, and sunshine—there is nowhere it does not penetrate and nothing it does not answer—and this is simply a matter of steadfastness. Steadfastness means emptiness within and selflessness.
'Agitated comings and goings; friends follow your thoughts.' When one is steadfast and undivided, there is nowhere one's influence does not reach.
If one is restless and agitated, using a selfish heart to influence things, then only those reached by one's thought will be moved, and those unreached will remain unaffected. Thus only one's companions will follow one's thoughts.
If a biased heart with attachments focuses on one corner or one affair, how could it be vast and universally penetrating? The Great Treatise says: 'What does all under heaven ponder? What does it deliberate?
In all under heaven they return to the same point through different roads, and arrive at the same result through a hundred deliberations. What does all under heaven ponder? What does it deliberate?'
The Master took the occasion of Influence (Wooing) to discuss the Way of mutual penetration to the utmost. Influencing things with a selfish heart of deliberate calculations makes the influence narrow. The principle of the world is one.
Though roads differ, their destination is the same; though thoughts are a hundred, their goal is one. Though things have ten thousand differences and affairs ten thousand transformations, when unified by the One, nothing can contradict it.
Therefore, when one rectifies one's intent, there is nothing in all under heaven that is not influenced and reached. Thus it is said: 'What does all under heaven ponder? What does it deliberate?'
How could one influence all things by using a selfish heart of deliberate calculations? The sun goes and the moon comes, the moon goes and the sun comes; sun and moon push one another, and light is born therein.
Cold goes and heat comes, heat goes and cold comes; cold and heat push one another, and the year is completed therein. Going is contraction, and coming is extension; contraction and extension mutually influence each other, and benefit arises therein.
This illustrates the principle of mutual influence through the contraction and extension of comings and goings: where there is contraction, there is extension; where there is extension, there is contraction—this is what is meant by mutual influence.
Therefore, sun and moon push one another and light arises; cold and heat push one another and the year is achieved; merit and function are accomplished from this. Thus it is said: 'Contraction and extension mutually influence each other, and benefit arises therein.'
Influence is movement: whenever there is influence, there must be a response; all movement is influence, and influence must meet with response. What is responded to becomes influence once more, and that influence again meets with response, so that it never ceases.
The inchworm contracts in order to extend; dragons and serpents hibernate in order to preserve their bodies. Penetrating subtle principles into the spirit enables practical application; utilizing application to bring peace to the body exalts virtue.
Beyond this, nothing more is known.
Having explained the principle of contraction and extension, external things are cited once more to illustrate it: the movement of the inchworm first contracts and then extends; for without contraction there is no extension, and after extension comes contraction.
Observing the inchworm reveals the principle of mutual influence. The hiding of dragons and snakes is how they preserve and rest their bodies, after which they can surge forth vigorously; without hibernating they cannot surge forth.
Movement and rest mutually influencing each other are contraction and extension. The noble person immerses the mind in subtle principles and enters the marvelous spirit in order to bring them into application.
Immersing the mind in the subtle is accumulation; carrying it into application is dispersion. Accumulation and dispersion are contraction and extension.
Utilizing application to bring peace to the body exalts virtue: following upon the practical application above, this means that making one's actions beneficial and dwelling in peace exalts and expands one's virtue and enterprise.
When one's actions accord with principle, affairs are correct and the person is at peace; the sage's capacity reaches its limit here. Therefore it says: 'Beyond this, nothing more is known.' Exhausting the spirit and knowing transformation is the fullness of virtue.
Having said 'beyond this, nothing more is known,' he concludes with these words, stating that exhausting the marvelous reaches of the supreme spirit and knowing the Way of transformation and nurturing is the supreme fullness of virtue, beyond which nothing can be added.