AVATAR
Eywa
Woodsprites are interpreted as signs from Eywa.
"Who's Eywa? Only their deity! Their goddess, made up of all living things. Everything they know! You'd know this if you had any training whatsoever."
- Norm explaining Eywa to Jake.
Eywa is the guiding force and deity of Pandora and the Na'vi. The Na'vi believe that Eywa acts to keep the ecosystem of Pandora in perfect equilibrium. It is sometimes theorized by human scientists that all living things on Pandora connect to Eywa through a system of neuro-conductive antennae; this often explains why Na'vi can mount their direhorse or mountain banshee steeds and ride them immediately without going through the necessary steps required to domesticate such wild animals.
In Na'vi Mythology
Some believe that this interconnectedness, which on Earth is merely a spiritual concept, exists in a physical and tangible way on Pandora, in the form of a strange, collective psionic consciousness embedded in the planet, drawn from all Pandoran life. It is, in a way, a little like a huge biological internet; the trees being computer servers that store information. The Na'vi can upload or download memories from it using their queues and it can even be used for mind transfers in certain cases.
The Tree of Souls grants the Na'vi access to the psychic essences of their deceased, which is how the Na'vi communicate with their ancestors. The roots of the trees are capable of extending above the ground and connecting to the nervous system of any living thing, even humans. This is how Jake Sully's consciousness was transferred to his avatar permanently.
Avatar: The Game
RDA Storyline
In the Avatar video game, this psionic link can be manipulated by humans as well. If the player chooses to side with the RDA, then the main objective throughout the game is to gather three psionic crystals in certain areas and plant them near specific crystal willow trees, which are said to be where emanations of Eywa concentrate. This is done so that the willow trees resonate with the crystals’ combined vibrations, forming a 'song'. The songs collected from each willow tree can then be used to locate the long-lost Well of Souls. This allows RDA scientists to both find the Well of Souls and build an artificial psionic machine that emulates an aggressive version of the smaller willow trees' signals, which is then planted in front of the active Well of Souls. This allows the RDA to tap into Eywa itself, control the psionic consciousness, and take control of the moon itself to turn it against the Na'vi, thereby giving the RDA a decisive advantage. Eventually, the RDA is successful in these efforts, and is inevitably on the way to winning the war against the Na'vi and taking absolute control of Pandora. This only occurs if the player sides with the RDA.
Na'vi Storyline
In Avatar: The Game, the Na'vi can ride and control creatures, like the direhorse, ikran and thanator. However, the player does so without connecting to them physically, because the game does not display animated queues for the Na'vi characters. The in-game Na'vi characters, including the player, do have queues, but all are shown to be firmly fixed to their shoulders rather than the free-hanging braided queues visible in the movie.
This may have been a technical decision at the time; the Dunia engine does support the relevant dynamics, but the system was unused.
DS Version
In the DS version, Eywa selected Nok to be the Alaksi Nari or 'ready eye'. It was Nok's duty to collect information about the human threat for Eywa, and make her understand that they were a terrible risk to the entire ecosystem. She responded by unlocking vegetal chests and providing Nok with weapons.
Similar Human Deities
Eywa has been compared to a number of mythological figures and deities, such as Gaia (Gaea), Mother Earth, Mother Nature, the Triple Goddess, or God by those trying to explain the relationship between Eywa and the Na'vi. The Gaia hypothesis follows on that the entire biosphere acts like a single organism or at least a complex system (soft Gaia), or that the Earth is consciously manipulating the biosphere in order to make conditions more favorable to life (hard Gaia). Other comparable figures and entities include:
Jörð in Norse mythology, the personification of the Earth, similar to the Native Americans' religious views of the planet being one living entity.
Her title 'All-Mother' resembles that of the Norse god-king Odin, the All-Father.
More poetically, Eywa's embodiment as plant life may be a reference to Yggdrasil, The Tree of Life, a holy embodiment in Norse mythology. Yggdrasil is a tree, said to be the root of all life, sent to keep the natural order of life on Earth. It balances the three worlds: the god's world, man's world and the underworld.
The Maori earth goddess, Papatuanuku, who is believed to be the living embodiment of the earth and gave birth to all living creatures, including people. Maori also have strong, spiritual ties to the land, similar to the Na'vi.
The theological concept of universal selfhood, of a unified "flow of the universe" and natural world is present in Buddhist and Taoist philosophy.
Trivia
There is a similar ancient Celtic word deiwa (pronounced dey-wa) meaning "goddess".
Several fictional mythologies from other planets or fantasy settings are similar to Eywa, such as the Mother Jungle from the planet Ithor in the Star Wars Expanded Universe or Yavanna from J.R.R Tolkien's "The Silmarillion", who created all life, plant and animal, in the shaping of the world and works to protect the life of the world. In Alan Dean Fosters "Midworld" books, "Emfol" is also a jungle hive intelligence to which the native inhabitants who live in a "Home Tree" can connect mentally. It is also threatened by human mining operations.