The extent of a wizard's knowledge is limited to which spells a wizard knows and can cast. Magic may also be limited by its danger; if a powerful spell can cause grave harm if miscast, wizards are likely to be wary of using it. Other forms of magic are limited by consequences that, while not inherently dangerous, are at least undesirable. In "A Wizard of Earthsea", every act of magic distorts the equilibrium of the world, which in turn has far-reaching consequences that can affect the entire world and everything in it. As a result, competent wizards do not use their magic frivolously.