What is a Gnosis?

The Gnosis (plural: Gnoses) is a physical representation of the Heavenly Principle's control and laws over Teyvat. In the Fontain Archon Quest, it is revealed that the Gnosis are made using the remains of the Third Descender. They were created as result of the war between the Heavenly Principles and the king of the seven dragon sovereigns, Nibelung. They created the gnoses as part of a "new order". Through this, the Archon War was launched as gods seeked to claim the gnosis, and seven were chosen. It has also been suggested by Nahida (Buer) that destroying a gnosis has the potential of awakening the Heavenly Principles, who have been asleep since the cataclysm.
The gnoses take on the appearance of a chess piece and typically reside within the Archon's body (usually the chest area). The current ones that are known is the anemo gnosis, which takes the form of a queen, the geo gnosis, which takes on the form of a rook, and the electro gnosis, which takes the form of a bishop.

How are they involved in the main story?

The main antagonists of the main story of Genshin Impact, the Fatui (diplomatic and military force from the cryo nation, Snezhnaya), are seen collecting the gnoses for purposes unknown. In Mondstadt and Liyue, one of the eleven Fatui harbingers (leaders/captains in the Fatui), La Signoria, is seen claiming the gnosis. She forcibly took the anemo gnosis from Venti (Barbatos), and made a contract with Zhongli (Morax) to claim the geo gnosis. In Inazuma, another Fatui Harbinger, Scaramouche, is given the electro gnosis by Yae Miko in exchange for the life of the traveler. As for Sumeru, Nahida is able to reclaim the electro gnosis, however gives that gnosis as well as the dendro gnosis to the 2nd ranking Fatui harbinger, Il Dottore, in exchange for wisdom. Finally, in Fontaine, because of the death of Focalors, Neuvillette (the hydro dragon of the seven dragon sovereigns) is able to reclaim the divine throne. In return for assissting in dealing with the prophecy, he gives the hydro gnosis to the two harbingers, Arlecchino and Tartaglia. At this moment, the Natlan archon quest is still incomplete, but it is confirmed that the pyro gnosis is still in the hands of Mauvika (Haborym).

What is the theory around it?

The main theory surrounding the Gnosis is the idea that each gnosis being a specific chess piece correlates to the Archon's role in the story in someway. Such as Venti's gnosis, who is the queen, and the queen is often considered to be one of the strongest pieces on the chess board. As such people use this to stregthen the "Venti is one of the strongest" theory. Although the more popular version of this theory is that the chess piece represents their ideal in some way. Such as Zhongli being straightforward and the rook being able to only move straight in 4 directions. The theory also applies to people prediciting what each Archon's gnosis will look like, such as predicting that the hydro and pyro gnoses are knights or that the cryo gnosis will be a rook.

Fun fact: There are only 4 official renders of the gnosis so far (anemo, geo, and electro), with the Pyro gnosis making an appearance in the version 5.1 trailer (at the time of writing this at least). There have been leaks of the dendro gnosis but it has yet to make an offical appearance within the game itself.

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