One step at a time
It is not easy to find a good access point into System’s-Theory, because there is non. Like standing at a cold pool, dipping your toe, it seems getting colder and colder, if you do not jump. So, the only plausible course of action is to just jump in. It helps to read the older articles first.
The implication of the other side | Das Mitsehen der anderen Seite | Observation of the first order | Beobachtung 1. Ordnung
We already established observance (Beobachtung 1. Ordnung) as the actualization of a difference (Unterscheidung), while marking only one side of this difference, but implying the other. That is defined as the observation of the first order.
Again, obervance does not mean “seeing”, but it is a great analogy and at times very helpful. Think of focusing on one thing while keeping the other “in the corner of your eye”, that is basically what “Mitsehen” means. So if we observe “good”, it is not just “good” (that alone would be a reference not an observance) but “good in difference to bad”.
The other side is not necessarily the opposite, but contingent. It could be good/bad or good/pumpkin or whatever, but the interesting differences are of course polar opposites.
But you can observe whatever you want, well, you can’t, of course, there is no you observing anything, because “you” IS an observation and only observance is observing. No observer, no you, just the actuality of the operating system.
Observation of the second order | Beobachtung 2. Ordnung
That is just an observation of the first order, that is actualizing a difference with differences on each side.
For example: “We” could observe red and thereby actualizing the difference of red/green (observation 1. order). Then “we” could observe stone, actualizing the difference of stone/wood (also 1. order). If “we” then actualize the difference of these two differences red/green // stone/wood, “we” got an observation of the 2. order. Maybe that leads “us” to onother observation, for example: color/material. Every observation of the second order is also an observation of the first order.
Reminder: No observer, no we, no us, just the actuality of the operating system.
The one-sided duality | Die einseitige Zweiseitenform
The German word is not duality but Zweiseitenform, which literally means a form, that has two sides, which is de facto the difference that is actualized, whenever observance is operational. But as we already established, even if the other side is implied, only one side is marked or referenced. So in that sense the way observance actualizes a difference is one-sided.
We only say good but we imply bad as the other side of the difference, because good alone would have no meaning [*]. And again, in System’s-Theory, there is nobody who could say anything, but it might be helpful to phrase it like that, for old times’ sake.
The unity of the difference | Die Einheit der Differenz
We already talked about the environment of the system, it is whatever system is not. So the system is basically observance in action and observance is a form of Sinn. Sinn is defindes as the difference of actuality/potentiality and also as the medium of the system, transcending all its forms [totally established].
So let’s unpack this. We got a lot of very interesting differences of polar opposites here: system/environment, actuality/potentiality, form/medium and also immanence/transcendence.
The interesting part is that, when observance observes „the environment of the system“, whatever is observed is not „the environment of the system“, because the system IS de facto observance [*].
The actual environment of the system is unobservable. If it was observable and observed, it would be system, but that is exactly what it is not and therefore: The unity of the difference system/environment is system.
The unity of the difference of actuality/potentiality is actuality.
The unity of the difference of form/medium is form.
The unity of the difference of immanence/transcendence is immanence.
[All that is established]
If one side of the difference is unobservable, the observation (and true understanding) of the unobservable implies the transcendence of the one sided duality and the form of the observation is then transcendental. [Heresy!]
The transcendence of the one sided duality is the necessary precondition of truly understanding the unity of the difference. [Heresy!]
If we use the picture as an analogy, the moment of sticking out your head is the moment of transcendence. It is a state of absence from the world, you’re there but you are not there.
When you pull back in your head, you might need some time to process your former state of transcendence, but if you successfully integrate your transcendent state, you can now truly understand as transcendental, what used to be just a hollow reference to the formerly unobservable.
Don’t get me wrong, the unobservable is still unobservable, but you might have opened your third eye that can see beyond what for the dualistic system always remains unobservable, while you (that is not you anymore) move along, building your first base in Trinity. [Heresy!].
This state of trinity is what I call the observance of the third order (Beobachtung 3. Ordnung) [most evil Heresy!].
Eventually we learn how to control the state of mind, so we can -at will- switch between transcendent (deep meditation) and integrated states (observance of the 3. order), but once you stick your head out, nothing will ever be the same.
Just like when you learned the rules of chess. You can never look at a chessboard again and just see nice figurines, you now see potential movement, constellations, interconnectedness, where there used to be egoic figures you once had mistaken for meaningful and real and yourself as one of them. 
As I said, transcendent states are useful for meditation, you stick your head out at will, just for fun, healing and downloading new information, but just as important is the integration of all that information (securing and maintaining the observance of the 3. order) AND what becomes a very important task of the whole Integration process:
To rebuild the ego, this time not as an empty shell we falsely identify with, but as a tool, a psycho-social conditioned coproduction, the functionality of interaction within duality.
As we begin to accomplish that, we are in the process of closing the circle and the resistance we still might feel, is our now alter ego, desperately trying to preserve itself.
Closing the circle is the death of the false identification with ego, the rebirth of ego as a functionality and therefore the movement into a new system that has successfully transcended and integrated the old one: Trinity.
[*] For the critics: nobody gives a fuck about reference, that would lead in an endless maze of shit, so let’s just forget about the reference, we care about observation. :-)
 Think of the difference between the knots of a net on one side and on the other side the net itself, where the knots are only points of culminating interconnectedness.
Estimated reading-time: 5 minutes.
Recommended reading time: 7 years.