A Wizard of Earthsea. Le Guin Ursula

Ged enters wizard school to learn the rules of magic. Headstrong and naive, he accidentally unleashes a terrible shadow-creature into the world. To correct the balance, he must face and destroy the shadow, whatever the cost. Ged's quest takes him to the farthest corner of Earthsea - a land of fearsome dragons, jealous wizards, darkness and light-where he will meet his destiny.