A book could be written about the fascination Paris sewers hold, not only for twentieth-century tourists but for much nineteenth-century literature. Hugo, however, sums up neatly their persistent attraction for the inquiring mind: their technical ingenuity, their participation in the romance of "secret passageway," their grim summation of human existence.
Hugo skillfully weaves them into the epic pattern of his novel. They not only serve as counterpart to the passage in which he describes the "underworld mine" of criminal Paris, but provide him with a structural, picturesque, and psychological climax to a long sequence of similar scenes. Jean Valjean had fled alone in fear, carrying the beloved burden Cosette; now he flees with Marius, carrying hatred and despair on his back. He has experienced many scenes of darkness: darkness lit by a crucifix in the bishop's chamber, darkness lit by the moon with Cosette at the well, darkness lit by a flaring torch at the barricades; but now the darkness is total and absolute.
And the darkness is within his soul as well. He has saved Marius, but this has not freed his spirit. He is still drowned in hatred, and there is not a glimmer of comfort or hope upon the black path before him. Like Aeneas, like Dante, Valjean has descended into hell, but it is only a last stage on his journey into light, and as he emerges from the sewers he emerges, through prayer, from his spiritual torment also.
The deeper significance of this emergence into the light of the friendly stars is underlined by the presence of Thénardier and Javert, standing like Charon and St. Michael upon the threshold of a better life. Thénardier has always been Valjean's criminal alter ego, and even now for a moment Thénardier's evil magic seems to work again, making us wonder whether Valjean has not after all really killed Marius. But in the face of this new Valjean, Thénardier's influence ebbs, and he meekly opens the door to freedom. Javert, the avenging angel, is a more implacable doorkeeper, but judgment must always precede paradise on Resurrection Day.
