Gaiaterra: Elysea's Conflict/The One Power

The One Power emanates from the True Source, which is made up of two complementary parts: saidin, the masculine half, and saidar, the feminie half. People who can wield it are called channelers.

The Past
Back in the past, around the Age Of Dawn, saidin and saidar were considered as two halves that can only be wielded by one gender. With males only able to channel saidin while females could only channel saidar. These channellers would form as the Aes Sedai. They aided the war-torn lands as scientists, healers, and philosophers. Women used saidar and men saidin, which led to the rise of the kingdom of Ylisse. But all of it collapsed near the end of the age as an Aes Sedai research team at the Collam Daan ripped open a hole for Dark Ones (what they called the Chaos gods). The researchers, headed by Mierin Eronaile, thought they had found a power that both men and women could wield. They were not entirely mistaken, as it was the same power wielded by the Heralds, but it allowed the Dark One to manipulate the darkest desires of those that lived in the Age of Dawn. What followed was a general collapse of civilization over the course of 100-110 years, concluding in the War of Power. It is said that, during this time, almost half of all Aes Sedai went over to the Shadow.

In the end, the Dragon, with the help of the Hundred Companions, resealed the hole, but the Dark One's delivered a counterattack that tainted saidin itself, a plague meticulously crafted by Nurgle, eventually driving all male channelers mad. This event led to an event known as "The Breaking" in which the Heralds used male channellers as weapons to wage a third incursion, leading to the formation of the seven Ajahs and the White Tower. And it would only be at the end of Iron when saidin was finally cleansed.

It was only by the Industrial Revolution that the One Power was examined again as they began noticing strange phenomena. As men and women, who often say that they feel that they're in the wrong body, began channeling the opposite power, this moment also coincided with the age where gender dysmorphia was looked into rather than being called a curse, and the slow disintegration of there only being male and female as transgender, non-binary, and other identities are accepted rather than looked down upon. And while it took towards the end of the Industrial Revolution the Aes Sedai found a startling revelation.

The One Power wasn't as gender locked as they thought, but instead by how someone leans towards either masculinity or femininity, and that the gender locked thought was from years of believing it that way.

Thus in modern time men and women who can channel are now given the choice of which path they want to channel as, the headstrong saidin or the analytical saidar, depending on preference. Though there is still some gender bias as around one-eighth of saidin/saidar users are women/men.

Nature of the True Source
It can be seen as a source, quite literally, of energy capable of manipulating the universe, which prolongs the lives of its users by a factor of ten or even more, depending on individual strength, though this is common of all magic users from the sorcerers of Chaos to psychics of the Collective. It is never used up by someone channeling it, only woven into a purpose temporarily. In the past each half of the One Power can be used only by people of the associated sex, though by who channels what half depends on their temperament and preference.

The two halves are direct opposites, yet both complement each other. The essential differences in the nature of the two halves of the Power mean that a saidar user cannot teach a saidin user to channel, and vice versa.

Channelers
Not everyone has the ability to "channel," or access, the One Power. Most have none at all, and some only have the ability to be taught, to one degree or another. But a few channelers are born with "the spark," an innate inclination that will lead them to touch the Source whether they wish to or not. These untrained channelers, sometimes referred to as wilders often die without ever gaining control over their innate ability by a strange sickness; some research indicates the mortality rate for untrained channelers is 75% or more. Often, however, survival comes with a price; Wilders may not even know they are using the One Power to do things. They just know that sometimes, "things happen" when they want them badly enough.

Wilders is also frequently saddled with a block, an instinctive self-preservation instinct that causes them trouble when they do try to channel purposefully. For example, these blocks can take the form of only being able to channel while angry, or only with one's eyes closed. Those who do not have the spark can go their entire lives without touching the Power, or even realizing they can. Within a short period of time after Wilders first channel without training, they will suffer side effects, of which there are many, such as fever and chills, or taking uncharacteristic risks. These side effects will bring the untrained channeler increasingly closer to an incident of touching the Power until they coincide. At this moment, without the proper training, the channeler will most likely die soon "as though an invisible clock had begun ticking."

Channelers must always be careful, as the One Power is dangerous. Besides providing an addictive stimulating effect, channelers who draw too much of the Power into themselves can kill themselves or render themselves brain-dead. If they are lucky--relatively speaking--they will only burn the ability to channel out of themselves, leaving them unable to channel ever again.

Channelers can also be permanently denied the Source by another party. In modern Aes Sedai parlance, this is called "stilling" when done to women, and "gentling" when done to men, but archaically it was called "severing" for either gender. Regardless of the circumstances, those who lose the ability permanently also tend to lose the will to live, though again this is something all magic users suffer.

Weaves
Channelers of the One Power cast their spells by "weaving", which is a combination of One Power flows manipulated by a channeler to elicit a specific effect.

There are five different flows that can be manipulated with the One Power: Air, Earth, Fire, Spirit, and Water; these are known as the Five Powers. Each of the Five Powers produces a different effect when woven. For example, weaving Fire on a candle wick ignites it, lighting the candle. More complex weaves require more than one flow to be used, but produce more spectacular results.

Theoretically, weaves of the One Power are similar to textile weaves, and weaving Saidar has been compared to folding silk. Once a weave has been created, the channeler can "hold" it to keep the effect ongoing, or knot the flows, a process called "tying the weave off". A weave that has been tied off persists even after the channeler has released the True Source or left the area.

Recently civil discussions have sparked between the Aes Sedai and the Menders of Cantha as both have noted that they cast their spells in a similar way.

Differences
Saidin channelers as a whole usually are much stronger in the amount of power that they can hold than Saidar channelers of comparable level (in much the same way men are generally stronger in their muscles than women) but the saidar can compensate for this lack of brute force with far more dexterity. So in all the things that only rough power is not needed, the strongest saidar channelers can accomplish with the One Power exactly the same as the strongest saidin channeler.

An advantage of the saidar is also that only saidar channelers can start the link for a circle, while saidin cannot link to form a circle of multiple channelers working together. Women are more dexterous in the actual weaving of the flows, allowing them to make complex spells more easily then saidin, and have the advantage of linking, but cannot increase a circle beyond thirteen.

When a saidin channeler and a saidar channeler work together they are much stronger than many of the same channeller, it is said that this is caused by saidin and saidar resonating, which means that the two Powers are working better together.

When using the One Power one weaves flows of different elements: Earth, Spirit, Water, Air, and Fire, also known as the Five Powers. Saidin is generally stronger with Fire and Earth, while saidar is generally stronger with Air and Water; significant strength in Spirit is distributed equally, and relatively rare in either. Great strength in all Five Powers has been unknown since the Age of Legends. Even then it was extremely rare.