There are three base elements that make up the universe; Light, Darkness, and Material, although some claim vacuum as the fourth, as it is necessary to all function.
Darkness is the most well studied element. It suffuses the vast majority of the world, granting substance and size to all common materials. Its aspects are believed to be shielding and healing, granting form and stature.
Light is the second most studied, although much less popular, as while it facilitates almost all movement, direct exposure causes extensive decay very rapidly, neutralizing the Darkness that suffuses it.
Material is the last and least studied element. It is fractal in nature, and infusing it with Darkness will cause it to swell indefinitely, although it does have a minimum size that it cannot be reduced beyond simply by removing the Darkness. Its shape can determine the propagation of Light through it, forming the basis for reactions and movement. In its pure form, it is called a Prism, and is capable of manipulating Light without taking damage in the process. This may occur naturally in some people, although the phenomenon is not widely observed, and has not been studied.
An interesting phenomena has been observed, in that when dense concentrations of Light or Darkness are gathered, they can be used to affect significantly more than a larger but less pure mix. This has led to much speculation, and the currently dominant theory is that what can be manipulated of Light or Darkness is merely a marker for an external force, that proceeds to act on its opposite on a rapid but periodic basis, and appears in larger concentrations when its markers are closer. This has also done very little to dissuade the religion that anthropomorphizes them, and is seen as evidence for the universe being two gods locked in combat.
Perhaps most notable, however, is the fact that People can manipulate Light and Darkness, separating them out and concentrating them. This allows manipulation of the environment, by spreading Darkness to reshape matter, and the strategic destruction of obstacles, by projecting concentrated light at them.
The first, known as Darkshaping, is widely studied, well viewed by society, and a somewhat popular vocation, as it allows one great advantages in construction or movement, and can even be used to heal, if employed carefully.Lightweilding, on the other hand, is badly received in general, as it is extremely difficult to practice with any modicum of safety, only really good for destroying things, and remarkably difficult to stop externally. This has mostly restricted it to dangerous idiots, extensively trained military units, and a rare few reasonably sane, cautious individuals trying to study it, which has led to much less knowledge about its workings or advanced uses than its counterpart.