In "Araby," what is the nature of the boy's sudden realization?
Disillusionment. In what Joyce referred to as an epiphany, the boy of "Araby" transforms from an innocent child to a disillusioned adolescent as he realizes that his religious and romantic idealization of Magan's sister and the bazaar have been foolish. Added to this realization is the fact that the boy is alone in his anger with himself:
Gazing up into the darkness I saw myself as a creature driven and derided by vanity; and my eyes burned with anguish and anger.
It is at this point that the boy has matured, but this maturation is at the expense of the loss of the exotic dream--"innumerable follies laid waste"--that has sustained him in his loneliness and "sombre" neighborhood: In the shadows and browness of his neighborhood, he could watch Magan's sister's "dress swing as she moved her boy and the soft rope of her hair toss from side to side." The boy, like the knights of Arthur's tales, has held Magan's sister as his ideal:
Her image accompanied me even in places the most hostile to romance....through the shrill litanies of shop-boys...the nasal chanting of street-singers...I imagined that I bore my chalice [like the Holy Grail] safely through a throng of foes. Her name sprang to my lips at moments in strange prayers and praises which I myself did not understand....
Not only has the boy romanticized his infatuation with Magan's sister to the exotic level [Araby], but he has confused this infatuation with religious fervor. So, with his disillusionment of his romantic idealizing of the girl, comes also a certain degree of religious disillusionment.
Reduced to the petty life of the street whose houses have "brown imperturbable faces, and the bazaar in which only idle gossip takes place," the boy allows "the two pennies to fall against the sixpence in my pocket," a gesture symbolic of his knowledge that life is only filled with the mundane.