World

The World (世界) is used to refer to the concept of the planet Earth. The use of the term "world" as by magi usually refers to the universal rules that can be manipulated or taken advantage of by mankind. Others may use "world" to refer to the two distinct "wills" of the Earth, Gaia and Alaya-shiki.

Gaia (ガイア) is the will of the physical planet and nature that lives on it while Alaya-shiki (阿頼耶識), or just Alaya (アラヤ) is the unconscious and universal will of humans to avoid destruction--the basis of all human existence. They originate from Akasha, the Swirl of the Root, and thus an individual recognized as a hero by either spirit can be incorporated into the Throne of Heroes.

Gaia and Alaya each have their own interests, and they will work against each other in order to preserve those interests. They are not necessarily opposed to each other, but they are driven to opposition due to the fact that humans, wishing to continue their existence, often corrupt their planet in order to live. They are not to be confused with Aristotles, which are simply unique, powerful beings from certain celestial bodies. The creature closest to being the Aristotle of Earth is Archetype Earth.

History
While the Earth was still in its primordial stage, the god Ea was involved in the building of the planet. He was a pseudo-deification of the power of the planet by which primordial Earth’s surface, covered by magma ocean and gas, was moved, crushed, and stabilized. Many gods began the building of nations after the primordial planet became habitable by life. The planet had yet to settle into the physical laws observed by humans in modern times, and it was not as such until gods faded from the world.

The time before the modern era is referred to as the Age of Gods (神代), during which mankind was less populous and Divine Spirits were either more common or more active. This period is marked by a greater proliferation of Phantasmal Species such as the True Ancestors and Gorgons, and greater interaction between gods and mortals. This is the age of heroes and mythology, when rules of mankind and the world were different but this period ended many years ago. Even Magecraft itself is described as being closer to Magic in this era and Caster's abilities reinforce this concept.

The current age is identified as the Age of Man, where the gods disappeared from everyday life and the progressive decline of magecraft began. Satsuki Kurogiri introduced the theory that the decline, beginning toward the end of the Age of Gods, may have come about due to the extinction of the Unified Language, which may have been common during the period. Gilgamesh insinuates that the world was more antagonistic towards humanity in the previous era, noting that even he could not afford to needlessly slaughter people. During that period, humanity was closer to its origin and the power of Alaya was more concentrated, augmenting the weight of each human soul in comparison to modern humans.

Gaia
Gaia is a will extending from Akasha that preserves the order of nature, and it will crush paradoxes or anything else that disrupts that order. It will exist as long as nature exists on Earth. It uses spirits as a sense of touch, and anything that interferes with them is considered a contradiction to nature. Its goal is to preserve the beauty and life of the planet, and it is willing to eliminate humans if that is what is necessary in order to stop corruption and return it to its natural state. It doesn't care what happens to humans if a danger to them is present.

In the case of the death of the world, such as in Notes, it would not blame humans and would simply resign itself to its own fate as long as humans also perish. However, in Notes, since humans were able to survive without nature, Gaia feared such beings living on the dead planet, and it made a final dying wish to receive assistance from the other planets to wipe them out.

Alaya
Alaya is born from the will of humans wanting to survive even if it means eating up their own planet. Like Gaia, it also extends from Akasha. According to Touko Aozaki in the Paradox Spiral chapter of Kara no Kyoukai, its existence was theorized by Carl Jung.

Alaya desires to keep the human condition stable, and it will generally oppose anything or anyone that threatens that stability. This includes what it considers to be paradoxes, such as Magecraft, though it focuses its efforts on mages it deems particularly threatening to humanity. Alaya will even enlist the power of other mages through its Counter Force (see below).

Counter Force
The balance of power between the two wills is maintained by the the Counter Force (抑止力), also translated as Deterrents.. Each will has its own Counter Force, referred to as the Beast of Gaia (ガイアの怪物) and the Beast of Alaya (アラヤの怪物), which are manifestations of the two wills through which they influence the Earth. The Counter Forces have the role of guarding the existence of their respecive wills, but they themselves have no inherent consciousness. They are passive, reactionary safety systems, phenomena that exist to erase other phenomena, and for this reason they have also been called the Reorienters of Direction and the Protectors of Balance (抑止の守護者 yokushi no shugosha).

A Counter Force will only act in situations where factors capable of destroying either Gaia or Alaya have actively started working, and it will come into play to annihilate those factors. They are swirls of power without a shape or body that will adjust their magnitude in accordance with target to be destroyed; enabling them to have a greater force than the target to assure absolute victory. For example, If it is impossible for human hands to adequately stop the threat, it will take the form of a natural phenomenon to wipe out the designated area and its surrounds like it did to a currently lost continent. It cannot be witnessed and people are unable to consciously notice it.

Alaya
The Counter Force of Alaya usually manifests by pushing "receptors", i.e., normal humans who can function as mediums for the Counter Force, into wiping out the factor of destruction. Receptors will often change in personality as if possessed, and they will be given exactly enough power needed in order to eliminate the target. There are also those who willingly form pacts with the Counter Force, such as Joan of Arc and Archer, in exchange for power in life on the basis that they serve it after death. They are then revered as heroes and incorporated into Alaya as Counter Guardians after their deaths. It is considered an even exchange, as they receive fame and glory, as well as the ability to serve humanity with the power they receive. These Counter Guardians, the Beasts of Alaya, are forced to go beyond the standard of humanity to become heroes that will be used for eternity to remove threats. They will defend humanity from destruction, even if it means slaughtering the humans who would be responsible for said destruction. It is worth noting, however, that the Counter Force of Alaya cannot freely react to destruction caused by nature or the Counter Force of Gaia. Thus even though True Ancestors are the enemies of humanity, they are recognized foremost as spirits of nature.

The Counter Force is completely emotionless, and it will go as far as stopping actions that would have brought happiness to ten thousand people on occasions if it deems it necessary. The factors capable of destroying the world have become extremely frequent since the development of civilization, and the Counter Force is thus constantly at work saving the world from destruction. For example, it has slow corporations from deforesting the Amazon rainforest at a rate that would end the world in a year to a rate where it is impossible for anyone to notice or care about. Because Alaya considers arts like Magecraft and Magic to be paradoxical crimes against the homeostasis it works to protect, if any person reaches into Akasha and acquires knowledge of Magic, the Counter Force will activate and send a "red shadow" after them to kill them. Magicians surviving today were somehow able to somehow avoid the red shadow. Souren Araya took steps to guard his attempts to reach Akasha at the Ogawa Apartment Complex from being noticed by the Counter Force. Even though it is opposed to their art, Alaya may use mages to accomplish its own goals. For example, it enlisted Archer as one of its Counter Guardians.

There are few people who can be called heroes of Alaya; there is usually only one hero per generation, and not even saving the world itself is an action that makes someone into one. The right to be called a hero that surpasses human beings comes from doing an impossible task, an alteration of destiny. Even if a person didn't have the power of a hero, as long as a disaster that couldn't have been averted otherwise was stopped by their actions, they will be recorded as a Heroic Spirit.

Gaia
The Counter Force born from Gaia is centered around its will to survive. Its main goal is to protect the natural beauty of the planet, so it will let humans live as long as the world is safe. Gaia made a deal with Crimson Moon in order to create the True Ancestors as a natural defense system. There is also a Beast of Gaia is known as Primate Murder.

Future
The future of the planet is undetermined, with many possible outcomes available depending on the conditions present in the parallel worlds. The Mana Depletion of the world of Fate/Extra is caused by the Aylesbury Valesti causing a pole shift that caused the depletion of mana. The world of Tsuki no Sango experienced a similar pole shift and the decline of the human race rather than magecraft. The world of Notes died entirely, and humanity still occupied its corpse. Gilgamesh sees a future where, following the wishes of Çatalhöyük, humanity outgrows the planet and reaches for light millions of lightyears away.