(click on trigrams)
I don't know what came first, the trigrams or the hexagrams, but it does not really matter. They are both from the same fabric, so one was discovered first, but they both existed long before.
To find out about first or last - or about their common origin - read the "TOE-series" by Katya Walter
The text about the JunZi, the noble one, in the DaXiang is from someone with a lot of insight. He looked at the trigram images and then tells us what this combination means. Not everyone is able to see this or even less to act according to it, but a really noble person could. This is the JunZi in the text of the Zhou Yi, not someone specific, but anyone who has a noble mind.
"The noble one corrects the situation to solidify fate." B: "Nobility is the inner fiber which runs parallel with life, not against it." So it is not a question of 'doing good', it is moving with dao.
'Zi' is the seed, the son. For a Chinese man it was extremely important to live on after his physical death. A son continues the lineage from the ancestors into the future. The JunZi is the heir who is a credit to his ancestors. In extension the mind which is a credit to humanity. Zi is a term of respect, it is added to the names of men of the past who did great things: LaoZi, ZhuangZi, MengZi, KongFuZi (Confucius).
Heaven Qian, TIME.
The severe laws of universe of time and order.
Earth Kun, FIELD.
Space of the earth. Receptivity, nurturing power.
Thunder Zhen, SHAKE.
Quake. Thunderclap or earthquake, to shock, terrify, or to be shocked or terrified. The wake-up call.
Wind Xun, CHOOSE.
To elect, to choose. Yield, mild, submissive, insinuating. Image: Seals for officials who were elected, chosen.
Water Kan, HOLE.
Depression, pit, hole, snare, danger, crisis. Water moves according to the space it finds. Adapts and yet cannot be restrained. That makes it invincible and dangerous. Unfathomable.
Fire Li, DISCERN.
Brightness, separate, 'catching' something. Insight, the moment of 'now'. Order.
Mountain Gen, RESIST.
Hard to chew, straightforward, blunt, forthright tough. Mountain, solidity, dignity.
Lake Dui, OPEN.
Everything which happens between creatures or matter. Exchange, convert.
Hexagram 1, Qian: Heaven moves: firmness.
A noble one owing to his own strength never ceases.
A mind strong and clear like heaven together with actions strong and clear like heaven has a huge power. Qian, the name of both hexagram and trigram, means drought, it is the scorching heat of the sun, but also the fertilizing rain which bring the earth back to life.
Hexagram 2, Kun:
The basic disposition of earth is female.
The noble man carries everything with great generosity.
Kun, name of both hexagram and trigram, means passive force of realisation, receptivity, compliance, obedience, female. It is composed of earth with stretch-out or lightning. The space of the earth, and its mysterious nurturing power to make things grow.
Hexagram 3: The great image says:
Water and thunder: sprouting.
The noble man unravels the warp.
The strength of water is not to fight but to yield. For unraveling one has to yield or it will become an inextricable knot. Together with the power of swift action all knots of life can be disentangled.
Hexagram 4: At the foot of the mountain a spring wells up: Ignorance.
A noble man nurtures virtue by reliable conduct.
Obviously water has to do with virtue, bot here and in 29 it is mentioned. Here 'inside', the contents of the package. It reaches others through his 'being like a mountain'. But also the other way, through his conduct he shapes his own virtue.
Hexagram 5: Clouds rise up to heaven: Waiting for the rain to stop.
The noble man drinks and eats and reposes relaxed.
His inner life cannot be disturbed by anything, he is what he is, like heaven is what it is. Outside he adapts to how the time happens to be, without losing his character, like water can take any form but is always water.
Hexagram 6: Heaven associating with water is incompatible movement: contention.
The noble one, when he sets up affairs, plans ahead.
Water is not the one which acts on a spur. Feelings, apprehension, depth, they can follow a way, like water follows the grooves of the terrain, but not clear one. So the noble one finds the openings first, and then makes his affairs fit into the space and time.
Hexagram 10: The great image says:
Above is Heaven, below is the Marsh: treading.
The noble one distinguishes above and below.
He gives the ambitions of the people the suitable position
Zé, marsh, also means luster, sheen. See hexagram 58. Heaven is sky, heaven, nature, God, day, season. It is about the universal laws which regulate everything in and below heaven. In human terms about the inescapable inner laws of a strong and noble mind. But that is a modern way to describe it, the ‘individual’ with inner laws. I think 2000 years back they did not see them as inner, but rather as following heaven’s rules. So the noble one knows human ambitions, and sees heaven’s laws, and makes them fit together.
Hexagram 11: Heaven and Earth unite: Eminence.
The ruler fashions and completes the Tao of Heaven and Earth.
He supports mutually with Heaven and Earth their order.
He stands by the commoners.
When heaven expresses itself through the nurturing earth, then law and life are in perfect balance.
To be a noble one is not especially a quality one has, it is a choice, every day anew, or rather every moment. A small man can suddenly do something which makes him a JunZi in that moment.
Sometimes the choice is not very hard. When it is very clear what your ethic says you should do, you can do that without much doubt. But other times it can be extremely hard. Making a choice which goes against a big fear, against your survival instinct, against your hopes for your future. Then you are not only a JunZi but a hero as well. All the other figures, the king, the big man, the small man, the child, the prince, the wife, they are much more defined by qualities or position.
You cannot switch from small man to king just like that. The other way might be possible though. But any king, wife, big man can be JunZi. Or not. Or one moment and not the next.
For the JunZi in the ZhouYi is older than the idea about it in the DaXiang (Wings). In the beginning it was the son of a noble, a person. The one who, thanks to a noble background, knows what to do in certain circumstances, clever, experienced. He is the good hunter, the good advisor, the good teacher, leader. Anyone who does something which needs skill or authority, has to refer to his JunZi. Unlike the businessman who ruins his marriage when he is still businessman in bed, a JunZi in bed is the ideal of any woman. And a wife who is a JunZi the ideal of any man.