The Weave is the means by which raw magic is tapped into and used by spellcasters. The Weave is the way in which magic presents itself to beings for their use, and it flows throughout the world, touching almost every corner of existence, with exception of dead magic zones. The Weave is considered many things, including Mystra's body, the source of magic, all the studies of casters, arcane and divine alike, and the many energies and forces that exist around the planes. Casting a spell is merely telling the Weave to rearrange itself to create an effect.