Cecilia was not inclined to help—it was too hot, and whatever she did, the project would end in calamity, with Briony expecting too much, and no one, especially the cousins, able to measure up to her frenetic vision. (1.2.6)
Cecilia knows her sister well…
But hidden drawers, lockable diaries and cryptographic systems could not conceal from Briony the simple truth: she had no secrets. Her wish for a harmonious, organized world denied her the reckless possibilities of wrongdoing. (1.1.6)
Briony is a big old neat freak. You don't often think of neatness as a kind of hope or plan—but this quote suggests that maybe it is. Briony wants—or hopes or dreams for—a world with all the beds made and all the dishes washed. Which puts limits on what she can do, and also results in some horrible messes.
Briony was hardly to know it then, but this was the project's highest point of fulfillment. Nothing came near it for satisfaction, all else was dreams and frustration. There were moments in the summer dusk after her light was out, when she burrowed in the delicious gloom of her canopy bed, and made her heart thud with luminous, yearning fantasies, little playlets in themselves, every one of which featured Leon. (1.1, 3)
The first thing we learn at the beginning of the book is that Briony is writing a play. Just about the next thing we learn is that the production isn't going to live up to her hopes. This is a subtle signal that… life is filled with disappointment and despair.
This time she paused to peer out of the window at the dusk and wonder where her sister was. Drowned in the lake, ravished by gypsies, struck by a passing motorcar, she thought ritually, a sound principle being that nothing was ever as one imagined it, and this was an efficient means of excluding the worst. (1.9, 1.28)
Cecilia is, by the novel's lights, correct—nothing is ever as you imagine it, and every time you imagine something (like Briony thinking the rapist is Robbie, or Cecilia thinking it's Danny Hardman) you're wrong. Unfortunately, Cecilia imagining that imagining will exclude the worst is also wrong. Briony is not drowned in the lake… but she will accuse Cecilia's boyfriend of rape and ruin everybody's lives. Cecilia wasn't counting on that.
"Our dad says there isn't going to be a war."
"Well, he's wrong."
Marshall sounded a little testy, and Lola said reassuringly, "Perhaps there will be one."
He smiled up at her. (1.5, 1.64-67)
Jackson and Pierrot are telling Paul Marshall that there may not be a war. Paul is cranky because if there's no war, he can't sell all his chocolate bars. In this book, though, Paul gets everything he wants, so the world is plunged into war and millions suffer and die, all so Paul can have his dream come true and sell chocolate bars. Jerk.
He thought of himself in 1962, at fifty, when he would be old, but not quite old enough to be useless, and of the weathered, knowing doctor he would be by then, with the secret stories, the tragedies and successes stacked behind him. (1.8.44)
This is Robbie imagining his future life as a doctor. Since Robbie is not Paul Marshall, imagining a happy future and making plans seals his doom. Rather than healing people, he dies of infection. Which seems really like an excessively cruel punishment for not being Paul Marshall.
They could never be counted, the dreamed-up children, mentally conceived on the walk into Dunkirk, and later made flesh. (2.244)
Robbie is with the British retreat, and he's thinking about how all the men around him are thinking of how they want to get home and have kids. This is one of the few plans not by Paul Marshall which comes true: Many of the people who think about kids end up actually getting back to England and having kids. Robbie doesn't—but somebody does. There's also a nice suggestion here that kids themselves are hopes and dreams and plans, like babies are little imagined stories that come true. And there are a lot of kids milling around in the last section of the novel, remember—all of Briony's nieces and nephews and cousins. So maybe the book isn't entirely a downer.
That he could be cleared had all the simplicity of love. Merely tasting the possibility reminded him how much had narrowed and died. His taste for life, no less, all the old ambitions and pleasures. The prospect was of a rebirth, a triumphant return. He could become again the man who had once crossed a Surrey park at dusk in his best suit, swaggering on the promise of life […] (2.181)
This is a doubly doomed plan. In the first place, legally, a court wouldn't care if Briony went back on her testimony. And, in the second place, Robbie gets killed before she can recant anyway. The only rebirth he gets is in imagination—first his own, and then Briony's novel.
He intended to survive, he had one good reason to survive, and he didn't care whether they tagged along or not. (2.12)
Again, Robbie is punished for (a) planning and (b) not being Paul Marshall. There's a trend here…
She could still hear his voice, the way he said Tallis, turning it into a girl's name. She imagined the unavailable future—the boulangerie in a narrow shady street swarming with skinny cats, piano music from an upstairs window, her giggling sisters-in-law teasing her about her accent, and Luc Cornet, loving her in his eager way. (3.218)
This is a little tricky. It's Briony dreaming of life with the French soldier, Luc, who dies in her arms at the hospital. So it's his dream (he mistook her for his fiancée) which never comes true. But… Briony does actually marry, and the suggestion is that she marries a French husband (Thierry). So the dream kind of does come true, maybe. We don't ever really get to see the happy ending, but it's nice to know that maybe it's out there.