Symbolism, Imagery, Allegory
America is the final word and image of the novel. It is, as is often the case, an image of hope and opportunity, but Bellow adds a layer of irony:
That's the animal ridens in me, the laughing creature, forever rising up. What's so laughable, that a Jacqueline, for instance, as hard used as that by rough forces, will still refuse to live a disappointed life? Or is the laugh at nature—including eternity—that it thinks it can win over us and the power of hope? Nah, nah! I think. It never will. But that probably is the joke, on one of the other, and laughing is an enigma that includes both. Look at me, going everywhere! Why, I am a sort of Columbus of those near-at-hand and believe you can come to them in this immediate terra incognita that spreads out in every gaze. I may well be a flop at this line of endeavor. Columbus too thought he was a flop, probably, when they sent him back in chains, which didn't prove there was no America. (26.180)
Augie doesn't have much cause for hope—not for what he's really after. Augie wants the American Dream, but he's forever uncertain about what this dream really means for him. And so he can't live the dream. This is why he calls himself a failure, but it's also why he compares himself to Columbus. His failure doesn't prove there is no American dream—even for him.
We might say that Bellow is being ironic about the irony of the American Dream. The irony of the dream is straightforward enough: despite the dream's promise, success in America doesn't come to those with opportunity and ingenuity.
The American Dream is supposed to be something achievable if you've got the mind for it, the will to see it through, and the opportunities to get started. But for many people, maybe most people, these wouldn't be enough. For them, the American Dream is the dream of Tantalus—forever teasing what is forever out of reach. The hope of moving from rags to riches is an absurd hope.
Bellow could have ended it there, but he twists the irony around. Augie, who in one sense wants to live without illusions, refuses to give up hope even though his hope might be absurd. America still has promise, even when he's most down. After wrecking all chance to marry Lucy Magnus, Augie is angry, but his anger passes when he looks at the "snow-polished and purified blue" of the winter sky:
The days have not changed, though the times have…the sailors who first saw America, that sweet light, where the belly of the ocean had brought them, didn't see more beautiful color than this. (12.471)
Seemingly down on his luck, Augie will rise again. He'll "turn his eyes at last again to the weather" (12.480), remember he's looking at America, and keep on truckin'. Is he living an illusion? It's possible, but it's also possible his image of America might one day correspond to the real thing. If he's not an optimistic chap, he's a hopeful one.