In act 2, scene 1 of Lorraine Hansberry's A Raisin in the Sun, George Murchison has arrived at the Younger home to take Beneatha to a play. While he is waiting for Beneatha to get ready, George is accosted by Walter, who insults him about his shoes, his father's investments, and his college courses. Walter is actually coming on pretty strong, and George calls him out for his bitterness.
Walter's response is obscene and definitely bitter, for he highly resents George's success. “Bitter?” Walter says, “Man, I'm a volcano. Bitter? Here I am a giant—surrounded by ants! Ants who can't even understand what it is the giant is talking about.” He is on the verge of violence, and he maintains that no one is with him; no one supports him, not even his own mother.
George bites his tongue and says nothing until he is ready to leave with Beneatha. Then he sarcastically addresses Walter with “Good night, Prometheus.” Walter has no idea what he means, but George is deliberate in his insult. He is referring to Greek Titan Prometheus who stole fire from the other gods to give to human beings. As his punishment, Prometheus was bound to a stake, and an eagle forever feeds upon his liver.
Apparently, Walter's claim to be a “giant” triggers the idea of Prometheus in George's mind, but also, something is clearly “eating at” Walter, and George can tell that. Walter is ranting bitterly and making little sense. He is jealous of George and deep down wants what the other man has (like Prometheus wanted the fire) even though he would never admit it. Further, Walter feels cut off from everyone, alone in the world even among his family members who cannot understand his dream. In George's mind, he is much like the lone giant Prometheus, forever consumed by his bitterness.