Here are some of the core concepts that are frequently repeated throughout the text.

Advantageous Culmination Perceiving the Great Person

利見大人

Li's ultimate culmination of the development of energy is via the perception of the Great Person.

Kun says:

利西南得朋，東北喪朋。
Advantageous Culmination to the SouthWest obtaining one's equal;
to the NorthEast renouncing one's equal.

The principle here relates to how yin at its extremity transmutes to yang.

The Shuogua Zhang says:

坤也者、地也，萬物皆致養焉，故曰：致役乎坤。
As for Kun it: identifies with Earth,
Myriad phenomena all accomplish their nourishment how?
Due to the saying: the service of nourishment relates to Kun.

In this passage, Kun is the only trigram of the 8 not assigned a cardinal direction. All of the others are assigned directions. The one that is left over is the SouthWest.

The phenomena described here is carefully delineated by Liu Yiming in chapter 13 of Cultivating the Tao (translated by Fabrizio Pregadio).

The Wuzhen Pian says (tl Pregadio):

You should know that the source of the stream, the place where the Medicine is born, is just at the southwest -- that is its native village.

Lu Ziye says (tl Pregadio):

The medicine comes forth in the southwest, the position of Kun;
if you wish to seek the position of Kun, how could it be separated from that "man"?
I have disclosed the secret in clear words, and you should remember it;
but I am afraid that when you meet him, you will not recognize the True.

This is why we have a perceiving / seeing / comprehension of / realization of - the Great Person. It is not going to meet someone, it is an accomplishment of the principle of the return of energy from within deep stillness and emptiness. It is an appearance, an arrival of and realization of connection with something.

When spirit crystallizes in the opening of the heart-mind, yang is nurtured within yin.

With this culmination of energetic development, one has achieved the ability to replenish one's energy and accomplish oneself spiritually.

Qian line 2 says:

九二：見龍在田，利見大人。
Nine Second: Perceiving the dragon in the field, Advantageous Culmination perceiving the great person.

Field here is 'tian' and likely represents the field of internal cultivation in the lower abdomen, the 'dantian' elixir field.

So here we have the central true yang energy of line two manifesting an appearance of primal energy in the dantian.

And when this happens, it is advantageous to bring this into culmination so that one may perceive the true higher self of one's great person.

Qian line 5 says:

九五：飛龍在天，利見大人。
Nine Fifth: Soaring Dragon residing in Heaven, Advantageous Culmination perceiving the great person.

Heavenly energy covers from above and transmutes from below. In line 2 we see the principle of energy appearing after transmutation. In line 5 we see the principle of connecting with energy from above via the third eye.

So in both cases there is potential for the yang that is returning from the SW (one's abiding in Kun's capacity) to develop one's capacity for perception of the great person.

It is beneficial for these two manifestations of central yang energy to connect. This is like connecting the third eye to the lower dan tien and emptying the mind to fill the belly. One becomes aware of their higher self and works to integrate it within - thus attaining Advantageous Culmination.

This is not the energy of seeking a guru externally, but of mastering oneself internally.

The Noble Person having someplace to go.

君子有攸往

Jun Zi is the person of virtuosity who may or may not be actual nobility, but whose virtuous actions work toward accomplishment.

As can be seen in Qian line 3, a noble person applying Qian Qian all day long, but needing to remember when to stop and sleep.

This is the ambition that involves "having someplace to go."

This refers to a line leaving its position and going to work with another line in its position, often in the other hexagram.

Not Eating At Home

家食吉

Here it is advantageous to get out of the home and connect with other lines.

Fording a Large River

涉大川

China is home to many large rivers, and in the past not having an easy way to cross over one, would establish limitations as to where one could go.

When there is an auspicious omen for crossing a great river, it implies that there is potential for undertaking and accomplishing a task that might ordinarily have limitations and not be considered.

In a hexagram, two lines of the same trigram position may resonate with each other, but be challenged to cross to each other to accomplish their work due to obstacles. Sometimes it is advantageous to traverse the obstacle (ford a large river), sometimes it is not.

Pressing Strongly Forward

征

A journey of some distance, campaigning, committing troops to something, a punitive attack, an expedition, compelling submission, contesting - these are similar in scope to 'fording a large river', however they involve the use of forcefulness to get ahead. There is a tone of using strength to press for an outcome in a situation where something would not happen without something to expedite it.

Notably this applies to hexagram 54's Younger Sister Marrying. Hexagram 53 shows us that it is Advantageous for a woman to marry on her own terms following gradual progress. So when a younger sister marries, it is advised for her to not press strongly forward for finding a placement. Overall this hexagram relates to the desires of the heart and the risks of instant gratification over the rewards of delayed gratification. For the most part it is more advantageous to delay, so that one preserves what one has rather than using it up.

Only in the very beginning are the conditions ideal for such leaps, should they be appropriate. And even then, one is subordinate to the result. After the beginning, there is desire and posturing. When there is desire, it is best to exercise restraint, to be sure if something is real and that it may last. This way centrality is preserved and something may be had, rather than lost and used up.

Not Having Disaster, Blame and Regret

无咎

无 means without, not having, or letting there be none of.

咎 means calamity, disaster, ruin, along with the responsibility one incurs for making a mistake - fault and blame. And too the regret that goes along with this. Sometimes it means finding fault in others.

Generally I have found it best to translate this as "disaster, blame and regret", to encompass all three layers of implication.

Often 无咎 are presented together, and when someone added punctuation they kept these separate. In this cases I go with "not having disaster, blame and regret." There is often something that comes before this that is an active reason why we are avoiding disaster, blame and regret by doing something.

When 无咎 shows up within a sentence, I switch to "without" or "does not have" - depending on the previous words this either becomes more passive "auspicious without disaster, blame and regret", or more active "going toward does not have disaster, blame and regret."

When 无咎 shows up at the beginning, it is more of a "let there be no disaster, blame and regret."

This is one of the most commonly repeated concepts in the Yi, and treating it like this helps to see where we are being told that something needs to be done in order to avoid a less than ideal outcome.

Exerting Effort with Raised Alertness

厲

Often translated as 'danger', Li 厲 means to hone, sharpen, grind to an edge, being on edge as though in danger or peril, a sharp sound as in rasping or grating, inciting, urging, stimulating, raising / lifting up with effort, as in flying due to 'beating' wings, sharp, severe, harsh, strict, implacable, and the crossing of a stream fully clothed.

All of it together paints a picture of the focus without room for error that comes at a moment where elements are converging. This convergence relates to the edge meeting with efforting to get through something. The encouragement and stimulating connects with the need for heightened awareness.

We often get Li 厲 in conjunction with Zhen 貞 'Aligning Toward Completion', or Ji 吉 'auspiciousness'. There is a mark of the intensity of the situation but not necessarily a forbidding of the action. Like with hexagram 10's trodding on the tail of the tiger. The tiger is represented by line 5. It can tolerate line 4 but does not tolerate line 3, and bites it. This is part of the action of 貞厲, Aligning Toward Completion with strictness. With strictness on account of the restrictions of the situation perhaps, but not Aligning Toward Completion that is dangerous to think about. Aligning Toward Completion strictly navigating the converging edge. Aligning Toward Completion that is beneficial, but has no room for error and requires strictly accommodating the limitations of the situation to get through its danger. When the tail is stepped on in a way that does not necessitate a severe response, the tiger does not bite. When it is stepped upon in ignorance by those who over-step their place, it bites.

There is Captivation

有孚

Here is a word, fu, that is associated in modern times with having earned trustworthiness, related to guardianship, and inspiring confidence in.

However in the older times it was associated with captives of war, booty of war, sacrifices, etc.

All of this relates with the concept of Captivation. One can be captivated by something, and we could say that they are being held prisoner, or are fully devoted to something, and both meanings may be correct from different perspectives.

We can captivate some loot from bandits, and we can captivate the trust from the bandits after sacrificing their leader.

Thus having existence of Captivation implies that one has captured a thread of something, or been captured by it.

Hexagrams 5 and 6 both have manifestation of captivation because the energies press against each other attempting to capture each other. With 6 one is advised to withdraw so as to avoid entanglement while one can, while in 5 there is no withdrawal so one must wait and bear with the captivation.

However with hexagram 20 we see that there is a bowing instead of sacrificing, which appears to manifest a captivation of approval.

Understanding these concepts, we may apply them toward the auspicious circulation of energy.

Expression of Energy; Persuasion

說

Shui is a word that relates to explication and exposition. It has to do with Dui's 兌 'pleasure' or 'joy' contained within it. However this having of something to be pleased about comes from Dui's 兌 'openness' and 'receptivity'. Openly receiving, enabling something to become filled. This is the principle behind emotions. Having emotions, feelings, something can become expressed.

This expression is persuasive. It has a purpose and uses feeling as a power to drive something, in a direction.

Thus, Shui 說 and its persuasion.

Often it is read as 脫 instead and used for the meaning of releasing from.

This presumably makes sense in some cases, in 38.6 we have a drawing of the bow and then a releasing of the bow. In 4.1 we have releasing of the shackles. In 9.3 there is releasing of the spokes. In 26.2 there is releasing of the part that holds the carriage to the axle.

However, it appear this could also work using the principle of Shui 說's persuasion. 38.6's easing of the bow, persuading it being the opposite of its drawing - a character that also applies to stringing a bow, or a string on a musical instrument. There is an intensification happening here, something is becoming alert and poised against. With Shui we ease it with our persuasion, "its OK now".

In 4.1 we are persuading by using discipline and shackles as persuasive punishment.

In 9.3 and 26.2 we have two places where power is transmitted through the chassis of a cart to make it work. In 9.3 the power is being transmitted through to the spokes. In 26.2 it is being transmitted through to the part that holds the carriage to the axle. This is simply a different type of persuasion, one where power that has been built up finds expression, persuasion, in its doing of work to move the carriage. It is a transmission of power.

Especially for 26.2 this idea of releasing from struggles to make sense. This line is at the heart of the concentrated power. It is not 'released', but is at the peak of concentration. The Buddhist Yi Jing calls this 'concentration of insight'. The Taoist Yi Jing says this is where the firing process stops. This is where fusion unfolds, and where fire turns to light. This exists at the core of the principle of Shui.