Inception

Ariadne: "Why is it so important to dream?"
Cobb: "Because, in my dreams we are together."

"I'll come back and we'll be young men together again."

"You remind me of someone... a man I met in a half-remembered dream. He was possessed of some radical notions."

Mal: "What are you doing here?"
Ariadne: "My name is..."
Mal: "I know who you are. What are you doing here?"
Ariadne: "I'm just trying to understand..."
Mal: "How could you understand? Do you know what it is to be a lover? To be half of a whole?"
Ariadne: "No..."
Mal: "I'll tell you a riddle. You're waiting for a train. A train that will take you far away. You know where you hope this train will take you; but you don't know for sure. But it doesn't matter. How can it not matter to you where that train will take you?"
Cobb: "Because you'll be together."

Arthur: "It would have to be a 747."
Cobb: "Why is that?"
Arthur: "Because in a 747, the pilot's up top, and the first class cabin's in the nose, so no one would walk through. But you'd have to buy out the entire cabin. And the first class flight attendant..."
Saito: "I bought the airline."
[Everybody staring right at him. Saito just shrugs his shoulders]
Saito: "It seemed neater."

Cobb: "You create the world of the dream. We bring the subject into that dream and fill it with their subconscious."
Ariadne: "How could I ever acquire enough detail to make them think that it's reality?"
Cobb: "Well, dreams, they feel real while we're in them right? Its only when we wake up then we realize that something was actually strange."

"With the slightest disturbance, the dream's going to collapse."

"That many dreams within dreams is too unstable!"