Cobb: What is the most resilient parasite? Bacteria? A virus? An intestinal worm? An idea. Resilient... highly contagious. Once an idea has taken hold of the brain it's almost impossible to eradicate. An idea that is fully formed - fully understood - that sticks; right in there somewhere.
Eames: [Shows up while Arthur is in a gunfight] You mustn't be afraid to dream a little bigger, darling.
[Pulls out a grenade launcher]
Cobb: You're waiting for a train. A train that'll take you far away. You know where you hope this train will take you. But you can't know for sure. Yet it doesn't matter. Now, tell me why?
Mal: Because you'll be together!
Ariadne: What's happening?
Arthur: Your subconscious is looking for the dreamer; me. Quick, give me a kiss.
Ariadne: [She kisses him and then looks around]
Ariadne: They're still looking at us.
Arthur: Yeah, it was worth a shot.
Saito: Don't you want to take a leap of faith? Or become an old man, filled with regret, waiting to die alone!
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 turns and stares at him. Saito just shrugs]
Saito: It seemed neater.
Ariadne: Why is it so important to dream?
Cobb: Because, in my dreams we are together.
Cobb: [from trailer] Dreams feel real while we're in them. It's only when we wake up that we realize something was actually strange.
Cobb: Inception. Now, before you bother telling me it's impossible...
Eames: No, it's perfectly possible. It's just bloody difficult.
Cobb: What do you want?
Saito: Inception. Is it possible?
Arthur: Of course not.
Saito: If you can steal an idea, why can't you plant one there instead?
Arthur: Okay, this is me, planting an idea in your mind. I say: don't think about elephants. What are you thinking about?
Arthur: Right, but it's not your idea. The dreamer can always remember the genesis of the idea. True inspiration is impossible to fake.
Cobb: No, it's not.
A thief who steals corporate secrets through use of the dream-sharing technology is given the inverse task of planting an idea into the mind of a CEO.