One of the definitions for archetype is as a literary term used to express details. In James Joyce's "Araby," the darkness and blindness are models of behavior of the protagonists of The Dubliners from which this story comes. The blindness, for instance, represents the self-deception of these characters and their inability to surpass the trivial, while the darkness represents their religious servility.
Just as the boy's street is blind (a cul-de-sac) where the houses are sombre, so, too, is the boy/narrator blind and in darkness symbolically, and trivial just like the bazaar about which he has been disillusioned. His love is one-sided, and he deceives himself, perceiving his quest of Mangan's sister as though he were a knight errant who seeks the holy grail. In his religious servility, he conceives of his infatuation in this romantic way as he watches the girl stand in the lamplight with her hand on the railing much like that of the communion railings in church. Later, he imagines that he "bore [his] chalice safely through a throng of foes" and her name springs to his lips like a prayer. In an example of his servility, the boy states,
...my body was like a harp and her words and gestures were like fingers running upon the wires.
Joyce's story ends in a realization of romantic blindness and the darkness of despair. For, the boy of "Araby" stands gazing into the darkness in his realization that his pursuit of an ideal is unattainable.