Alonso Quixano—or Don Quixote, as he'll become—is a very well-read, intelligent man. He isn't by any means an acquisitive man, but he does have some possessions all the same. And his most prized possessions of all are his books. Alonso's books are hugely important, both to himself and to the story, because they act as a catalyst for the transformation of the humble Quixano into the valiant knight-errant Don Quixote.
Due to his extensive reading, Alonso becomes completely obsessed with tales of chivalry and courtly love. He finds the old romantic tales infinitely more interesting than his relatively drab, humdrum existence. Gradually, Alonso becomes deeply immured in a fantasy world completely divorced from reality. Due to a dangerous combination of too much reading and too little sleep, he genuinely comes to believe himself a brave knight—Don Quixote, no less—who must venture forth into a corrupt and dangerous world, righting wrongs and bringing justice to all those he meets.