[Ed. Note: Originally posted by pmog on GameFAQ’s FFX forum here (broken link): http://www.gamefaqs.com/boards/2000008-final-fantasy-x-storyline/21477330?page=9]
This is information that I’ve already posted a long time ago, but decided to rework and repost for the sake of completion. This is all taken from the FFX SUG.
Note: the actual word “pyreform” is me taking liberties with the original Japanese, in order to kind of tie in with the existing localisations. The original word “genkoutai” can be literally broken up into the characters for “illusion-light-body”, with “genkou” being translated into different things in English (eg. “moon” in “Moonflow” and “moonlily”, and the “pyre” bit of “pyrefly”). Believe me, it’s much more straightforward in Japanese. “Pyrefly-body” could probably also pass for a valid translation attempt. Incidentally, “genkoutai” is a term that doesn’t actually appear in the game, but is used by the creators and official sources to distinguish between “regular” objects (eg. people/animals/most other things) and fantastic phenomena (eg. aeons/fiends/people like Tidus/Auron/etc).
What Are Pyreflies
Pyreflies are things which hold the key to various phenomena that take place on Spira. They aren’t living creatures, as their name would suggest, but bundles of life energy, so to speak. They exist in low concentrations over the whole of Spira – even internally within people’s bodies. Pyreflies are usually invisible, but in such times as when a fiend is defeated or when a summoner performs a Sending, they give off light and reveal themselves. For that reason, they’re often mistaken as “arising when there is a loss of life”, but the truth is simply that in the aforementioned situations, they can be seen only because they’re condensed in high concentrations. However, because research into pyreflies isn’t very advanced, most people aren’t aware of their true nature.
Pyreflies can do things like react to people’s feelings and memories and bind them together with images, as well as store audio and visual information. Spheres are things which make use of these particular properties of pyreflies. Whether it’s recording messages on spheres, filming with sphere cameras, acquiring information from sphere monitors, and so on – spheres are becoming an essential item in the lives of the people of Spira.
The raw material for spheres is water that contains a high concentration of pyreflies. However, this kind of water can only be gathered from specific locations, such as the Macalania springs.
Fiends And Pyreforms
Most of the fiends found on Spira are things wherein the feelings of the dead who were unable to go to the Farplane have combined with pyreflies. Bodies that are composed of pyreflies in this way have been referred to as “pyreforms” – as opposed to “flesh-and-blood bodies.” Aeons, as well as the bodies of those who’ve remained in this world after their deaths, are nothing other than pyreforms. Pyreforms are sustained by the thoughts that are the cause of its creation – for fiends, it is hatred and envy of the living; for aeons, it is the dream of the fayth.
The Relation Between Pyreflies And Water
Pyreflies and water harmonise with each other extremely easily. Accordingly, water causes all sorts of phenomena in Spira. When summoners perform a Sending, the pyreflies on the water’s surface are fixed into place due to the summoner’s abilities, and it becomes a foothold. The blitzball sphere pool, too, is made by utilising the underwater pyreflies and congealing the water into a sphere. In addition, blitzball players being able to stay active underwater for long periods of time is because they are supported by the pyreflies that are contained in the water.