In the Manga and the 2009 animeEdit
In the Fullmetal Alchemist manga and 2009 anime series, the Gate is a pair of doors resembling large stone tablets engraved with a mural, floating in an endless white expanse. Though there appears to be nothing behind the doors when they are closed, upon opening, they reveal a dimension of information which manifests as a shadowy void with several shadow-like ethereal hands protruding from it and a single large eye within. The eye resembles those of the Homunculi created by Father and, indeed, the shapeless void and its extremities look very similar to the original forms of both Father and the Homunculus Pride.
Any alchemist who attempts a Human Transmutation is summoned before the Gate by the transmutation's rebound and is confronted briefly by the being known as Truth before the Gate itself pulls them through its doors. Inside, pure knowledge about the world, the universe, alchemy and everything is forced into the alchemist's mind as he or she begins to break down both physically and mentally, becoming part of the flow. However, the alchemist is only granted as much knowledge is proportionate to what is being given up as a "toll" through the Gate. For example, Edward Elric, who gave up his left leg as toll, only saw so much, but his brother Alphonse - who had given up his whole body - saw a bit further. It is unknown what happens to those alchemists whose lives are given up, but the Philosopher's Stone appears to be the only thing that would allow one to pass through the Gate without paying a personal toll. If an alchemist survives his or her passage through the Gate, they are sent back to the mortal plane without whatever they left behind as payment.
Though the Gate appears identically to any and all who pass through it, the engravings on the stone doors appear different to each person as a reflection of their true self and to that alchemist's understanding of "The Truth" (all the engravings, in one way or another, are representations of the Universe and the Cosmos). For Edward Elric, who has passed through the Gate no less than four separate times, the mural is a relief of 17th century Paracelsian scholar Robert Fludd's Sephirothic Tree of Life with numerous tendrils and branches, while the mural on Alphonse Elric's Gate is a relief of an illustration from 15th century alchemist George Ripley's text "The Marrow of Alchemy". For Roy Mustang, the mural depicts a stylized version of the Flame Alchemy array designed by Berthold Hawkeye and for Father, the Gate appears to be completely blank, likely because of his inability or unwillingness to learn, change, or grow spiritually during his lifetime. It is unknown what image appeared on the Gate for Izumi Curtis.
In Chapter 51, it is revealed that the Homunculus Gluttony was the result of a failed experiment by Father to create a new Gate of Alchemy through which he could access the whole of alchemical knowledge. As such, the eye that appears in the expanse of Gluttony's stomach (also enlarging his mouth) when he morphs to his true form is nearly identical to that behind the true Gate, but the space within him is pitch black and everything that has amassed from his eating habits just piles up inside. Due to this, Gluttony's Gate is full of all the objects he has eaten within a massive sea of his victims' blood.
In Chapter 104, it becomes apparent that both the Earth and the Sun have gates and that it is by harnessing the power of both that Father plans to achieve his objective.
In Chapter 108 it is established that the individual gate is what allows people to use alchemy. In the same chapter it is implied that the Gate itself can be used as a toll in order to retrieve something that was taken by the Truth, but its loss renders the person to whom it belongs permanently unable to use alchemy.
In the 2003 AnimeEditIn the 2003 anime, the Gate functions similarly to that of the original manga, appearing as a pair of doors in an endless white expanse and forcing the truth of alchemical knowledge into the minds of alchemists who are called to it by the rebounds of Human Transmutation, but its nature is different. Instead of being a source of alchemical knowledge, the Gate in the 2003 series is the origin of alchemical energy and a dimensional portal to another world - the Earth. It is explained that, when people from "our world" die, their souls become energy which passes through the Gate and becomes the energy used in everyday transmutations in the Fullmetal Alchemist world. Those who pass through the Gate are separated into three parts - the mind, body and soul - until emerging on the other side. For those unable to cross properly, parts of the mind, body or soul are taken by the Gate, but those who emerge whole on the other side find themselves in the alternate world. However, it is nearly impossible for those who cross into the real world from the Fullmetal Alchemist world to return, as alchemy does not work on Earth.
The Gate in the 2003 anime appears, not as stone tablets, but as a three-dimensional, moving version of Auguste Rodin's sculpture of the Gates of Hell from Dante's Inferno. Inside, rather than a black expanse with one eye, the space is filled with little shadow children with gleaming purple eyes, all of whom are set to attack beings attempting to pass through the Gate. It is one of these "Gate Children" who becomes the Homunculus Wrath after taking Edward Elric's arm and leg from him.
According to the series, the Gate can only be opened using three different methods:
- Using Human Transmutation to cross into God's domain.
- Activating the proper Transmutation Circle on the body of an infant, as infants do not have a strong bond between mind, body and soul and are therefore, closer to the nature of the Gate.
- Sacrificing a human or Homunculus in the proper Transmutation Circle.
- It is interesting to note that the Eyeballs that appear in the manga and 2009 anime whenever the Gate is summoned vary slightly between both media. In the manga, as seen in the few color pages and covers, the eyes have a slight reddish hue to them, but in the anime, they are pure, solid white in color.
- The details of exactly why the dub of Brotherhood decided to start calling "The Gate" the "Portal" midway through the first 15 episodes is unknown, despite it being "the Gate" in every single version of any FMA story, even on the official FUNimation subtitles.
- The mural on Edward's gate was designed by Robert Fludd, who was a studier of the works of Paracelsus. This seems like another view of the connection between Edward and his father Hohenheim, as Paracelsus is the person upon which the character of Hohenheim was based.
- The concept of the Gate of Truth could have come from the idea of "Akashic Records" or "Akashic library", an ethereal compendium of all knowledge and history. In this case, the Gate would be the Akashic library and compendium of all knowledge. The term of Theosophy was used during the Renaissance to refer to the spiritually-oriented thought and works of a number of philosophers, including Paracelsus and Robert Fludd.
- For some unknown reason, the design of The Gate slightly differs after episode 45 of the 2003 anime than it does in the earlier episodes and in the opening scene of Conqueror of Shamballa. A monument of a baby being held up appears on top of the gate that is not there in the other appearances. Its possible that it is a reference to the Gate from the manga, which differs slightly in appearance from person to person, as every time this version of the gate appears it is being opened by Dante, and the gate opened by Hohenheim and Alphonse in the movie had a completely different appearance.
- The Gate may also serve the purpose of reincarnation in the 2003 anime, as Alphonse said that his brother's soul was still at the Gate in episode 51. This would explain why babies still have strong connections with the Gate, & the Gate Children as being souls still reincarnating between both sides of the Gate. Furthermore it also functions as the afterlife of sorts, since both Ed and Wrath resided there temporarily (though the former was revived, while the latter chose the disappear into the hereafter.)
- As stated by Father, whenever an alchemist performs human transmutation and the alchemist is taken to the gate, the Truth takes the organ or limb related to the alchemist's "desire" as a toll, ironically unabling him/her to fulfill it - but providing them with a sort of "lesson" - , as seen when:
- Alphonse's whole body was taken, "losing the ability to feel the warmth he so desperately missed" (his mother's warmth).
- Edward's leg was taken, "the leg on which he stood, as well as the only family he had left" (his brother, Alphonse).
- Izumi Curtis's internal organs, so she will "never give birth to her so desired child".
- Mustang's eyesight, as he will "never see the future he so envisions".
- Though not stated by Father, Jude's eyes, so he will "never be able to look at his beloved Rosalie again."
- in the 2003 anime, it was heavily mentioned that The Gate exists within everybody, and the fact that Ed vowed to destroy it at the end of the movie, which would make it impossible to do so (because of the former), though he meant to destroy the one that his father created to return him back to Amestris, rather than destroying it in general.