The Aetherium / Outerworld

The Aetherium, called the Outerworld colloquially by non-scholars, is a place that resides "beyond existence". According to various authors from then and contemporaries, the Aetherium is a pocket universe that exists everywhere at every given time. Within this theorized world, every concept and idea resides there in a state of what's called "forms".
Forms are essentially the perfected forms of a given object or idea, this perfected form then manifests itself in our world as an imperfect reflection, this is the primary reason that the material plane is sometimes reffered to as "the mirror-world" as we are all reflection of imperfect forms.
A small addendum before i move on to more specific things: I call it theorized because it has never been actually observed by scholars, the only reason why they sort of accept forms as being true is because of the huge surge of magic users in the later years of the republic. The most experienced of these users explaining that they are "altering the forms", so scholars have reluctantly decided that there must be some truth to this world being a reflection.
While that is a basic explanation of what the Aetherium, there are some other complexities that warrant segments:

The two levels / the polarity view

Like all ideas, the Aetherium has seen a lot of "playing around with" by scholars. One particular emerged variant of it, is dubbed "the polarity view" and entails that the Aetherium being divided into two distinct levels. The first level is dubbed "Ether" and it is the place where all positive forms of ideas reside in, while the other level is called "Erebus", and as you can guess, is where the negative forms reside in.
This explanation arose mostly among moral absolutists, particularly the kind of a theological background to use as a suppliment for their religions. They made the argument that since there are absolutes in concepts (according to them), the place of origination must likewise be divided to reflect the two distinctions. This is mostly dismissed by the majority of scholars, but some due entertain that the binary might be a thing (for reasons I will go into later)

The dream pier

The title is not the actual moniker for this particular element of the Aetherium (I am however, heavily lobbying for it with my peers), but it's chosen to illustrate the supposed "access" we have to the Aetherium. According to some, when we go to sleep, our conschious recedes and finds itself transported to the Aetherium, where dreams subsequently take place as your disembodied mind begins constructing an "inner temple" (a dream sequence). It's with this connection that some have decided to dub the Aetherium as "the dreamworld", as calling it "the unconchious mind of reality" is a mouthful to the average individual.
When the mind is in the Aetherium, it seemingly starts pulling on forms and constructs the dream, the Aetherium then constructs a landscape for you. This landscape is then heavily influenced by the unconchious mind, and depending on it's state might pull on various forms, some that might be classified as "negative". Whenever these "negative" forms intrude upon the dream, they become nightmares.
Now Theologicians argue that negative forms invading the dream are their antagonistic figure sending their agents to sway you off a righteous path, while Psychoanalysts and Psychologists argue that negative forms intruding on dreams is underlying trauma or signals from the mind regarding their current mental state. Like someone suffering from PTSD and reliving the horrors of their experience in their dreams, an anxious person witnessing an upcoming event etc. Others believe it to be a bunch of bull. For scholarly integrity I will refrain from delivering my stance on the matter.

Origin of the Aetherium

(OOC: This segment will be returned to and revised once I have written the next article: Psycho-materialism)
To finish off this article; I will end with talking about one of the more interesting aspects to the discussion, this being it's disputed origin. This ties into the broader discussion surrounding the concept of Psycho-materialism.
Theologicians argue that the Aetherium is essentially "the next world", the place where their afterlives usually takes place (if they have one), and make the argument that the Aetherium came about from the conschious power of their creator diety. However, atheistic scholars are a bit more critical on the origin of the Aetherium, and it's importance. They believe that the Aetherium emerged, as a result of a desire to understand where everything came from.
Animals usually think of things in 1:1 relations, but people have a tendecy to overthink, and ask question to the origin of things. The theory goes, that at some point in the past some thinker conceptualized the idea of the Aetherium, which then became popular among people that quickly rose to such popularity that it manifested itself in reality (Beyond it, but you get what i mean). Part of this popularity, likely came from religious people seeing it as an idea they could leverage to create their afterlives, and also to make it easier to cope with the struggles of the current one, as there was always a next one that would be even better.
But that's one of the things we can't really know for sure.

Form laws / Covenants

Even tho forms are said to be altered based on the perception of conscious minds, there does seem to be some hard rules in place regarding their state. Psycho-Materialists argue that these supposed laws, are not set in stone, and can be altered if a higher conschious mind will them so. Since we have no records of people succesfully altering the forms beyond the following rules, they remain laws:

Covenant 1, Form theory/aspect arts can be used to heal injuries, however if the wound should prove to have been fatal, arts cannot be used to heal. If a person could recover from an injury naturally, they would be able to use arts to speed up the process. If they were to have their throat or wrist slit, they would not be able to heal themselves.

Covenant 2, You cannot resurrect someone who has passed away. (This covenant and the first one serve to establish a circle of life and death. Because without one, the other loses meaning)

Covenant 3, A form cannot be permanently altered, it can only be altered to the extent of the persons ability but will return to it's original state once the flow has been cut. If another form is altered by you using an altered form, it will remain changed. For example: if you light the grass around a tree on fire, the tree will catch fire and burn. Once you stop altering the form, the tree would remain burnt but the grass will return to it's original state.

Covenant 4, time cannot be altered, as it's a transcendent form that dictates the state of forms.

Covenant 5, you cannot force someone to change. As with the forms, a person follows the same guideline, they cannot be altered by an outside force.

Type

Universe