In chapter six of The Great Gatsby, Gatsby knows Daisy didn't have a good time at the party. What is Nick's advice? How does Gatsby react?
Nick, despite his own protestation that he is incurably honest, tries to sidestep Daisy's dislike of the party, though he has just told the reader that it "offended her—and inarguably ... She was appalled by West Egg, this unprecedented 'place' that Broadway had begotten ..." Rather than agree with Gatsby that Daisy didn't like the party, however, Nick responds tactfully and evasively, saying,
"I wouldn't ask too much of her ... You can't repeat the past."
Gatsby responds "incredulously," looking around him "wildly," and denying Nick's words.
"Why of course you can!" he exclaims, then goes on to say he is "going to fix everything just the way it was before." He talks about the past with Nick, and Nick realizes that Gatsby wants to start over because he has realized that something went awry—"had been confused and disordered"—ever since his time with Daisy, and he believes he can go back, carefully retrace his steps and get it right on the second try. This becomes, in microcosm, the fallacy underlying the larger American Dream as Fitzgerald describes it, that you can come to a new continent and start anew, erasing the mistakes of the past.
When Gatsby despairs that Daisy doesn't understand his feelings as she once did, Nick advises him to not ask too much of Daisy because the past can't be repeated. Gatsby reacts with disbelief, almost in panic at the idea:
"Can't repeat the past?" he cried incredulously. "Why of course you can!"
He looked around him wildly, as if the past were lurking here in the shadow of his house, just out of reach of his hand.
Repeating the past with Daisy had become Gatsby's reason for living, the dream he had pursued for the past five years. The idea that no one can repeat the past was completely foreign to him--the denial of the possibility of his dream being realized--and to hear such an idea from Nick was frightening.