In my opinion, Chapter 7 of The Great Gatsby contains the best quote revealing Daisy's character. Ironically, it isn't Daisy herself who speaks the quote, . . . it's from a conversation between Nick and Gatsby:
"She's got an indiscreet voice," I remarked. "It's full of--" I hesitated.
"Her voice is full of money," he said suddenly.
That was it. I'd never understood it before. It was full of money--that was the inexhaustible charm that rose and fell in it, the jingle of it, the cymbals' song of it. . . . High in a white palace the king's daughter, the golden girl. . . . (120)
Ah, yes, I don't teach Chapter 7 without reading THAT quote! It says more about Daisy than her actual diction ever could. (And it's one of the reasons why I have always wondered by Fitzgerald's Zelda could still hold her head up high, knowing she was the inspiration for this shallow character.)
Now on to Chapter 8. This quote is significant because of the grand symbolism behind it:
"I told her she might fool me but she couldn't fool God. . . . I said 'God knows what you've been doing, everything you've been doing. You may fool me, but you can't fool God.' . . . God sees everything." (160)
Let's deal with the symbolism first. Dr. T. J. Eckleburg, the giant eyes of an oculist on a sign overlooking The Valley of the Ashes, has always symbolized God, . . . but not the loving God of the Christians. No. It's a God who sees but doesn't care. A foreboding God. A desolate God. A God who does nothing to help poor Wilson who goes insane after learning about the adultery his wife has committed. This quote, spoken to Michaelis who is trying to help Wilson, is the beginning of proof of this insanity, . . . even before Wilson's murder/suicide success.
I like this quote from chapter seven in The Great Gatsby:
She had told him that she loved him, and Tom Buchanan saw. He was astounded. His mouth opened a little and he looked at Gatsby and then back at Daisy as if he had just recognized her as someone he knew a long time ago. (125)
Daisy then keeps talking normally because she doesn't realize anything has happened. This is a moment of realization for Tom, as he realizes that there is something going on he was unaware of. The simile in the final lines demonstrates his awakening.
In chapter eight, we read:
If that was true [that Gatsby knew with certainty that he had lost Daisy] he must have felt that he had lost the old warm world, paid a high price for living too long with a single dream. (169)
The dying of Gatsby's dream here is poignant, special. The dying of a dream usually is. Gatsby's loss is even more moving, in that his dream never was. He had thought to recapture the past, but it was a past that never was. His illusion is destroyed.