4 ideas
At the school on Roke, the student Ged is stung by his rival Jasper's contempt and, to prove his power, attempts a forbidden spell to call up the spirit of a dead woman. The spell tears a hole in the world and lets through a shadow creature that mauls him and kills the Archmage Nemmerle, who spends his last strength closing the breach. Ged's pride, not lack of skill, is what makes his real ability dangerous.
While Ged runs from the shadow, it grows stronger and pursues him across the islands, and it nearly possesses him. When he turns on the advice of his old master Ogion and hunts it instead, the power shifts and he becomes the pursuer. Avoidance does not keep a fear at a distance. It gives the fear the initiative.
In Earthsea every thing and person has a true name in the Old Speech, and magic works by knowing it. To know a thing's true name is to have power over it, so people guard their own names and reveal them only to those they trust completely. Knowledge of a thing's essential nature, not force, is what gives a mage control over it.
Ged defeats the shadow by speaking its name, and its name is "Ged"; the two merge and he becomes whole rather than destroyed. The dark part of a self cannot be destroyed or outrun, only acknowledged and taken back. On this view, wholeness comes from integrating one's capacity for harm, not from purging it.