All magic has a Source of Power: a source that a character can pull power/energies from in order to create a magical effect. Power comes from within and from the environment and the energies of the world around. It requires self-discipline and an ability to reach into one's self in order to be able to reach out to the energies of the universe.
In order to gain access to any of the other Sources, a character must have access to the Mental Self ability. All spells require an effort of the individual's mind or Will, which comes from a combination of Wisdom and Constitution.
These are those sources:
Many spells also require a material component, but points can be spent to eschew materials.