FRANKLIN: Yes, Clarence. A man down on Earth needs our help.
CLARENCE: Splendid! Is he sick?
FRANKLIN: No, worse. He's discouraged. At exactly 10:45 p.m. tonight, Earth time, that man will be thinking seriously of throwing away God's greatest gift.
CLARENCE: Oh, dear, dear! His life! Then I've only got an hour to dress. What are they wearing now?
This is our first inkling of how bad things are going for George. This goes way beyond dissatisfaction.
GEORGE: I couldn't face being cooped up for the rest of my life in a shabby little office. Oh, I'm sorry, Pop, I didn't mean that, but this business of nickels and dimes and spending all your life trying to figure out how to save 3 cents on a length of pipe ... I'd go crazy. I want to do something big and something important.
PA BAILEY: You know, George, I feel that in a small way, we are doing something important. Satisfying a fundamental urge. It's deep in the race for a man to want his own roof and walls and fireplace, and we're helping him get those things in our shabby little office.
There's some foreshadowing in the language here: George "couldn't face" staying in Bedford Falls; he'd "go crazy." This exchange also sets up the film's conflict between George's dreams and how his life actually turns out.
MARY: What'd you wish, George?
GEORGE: Well, not just one wish. A whole hatful, Mary. I know what I'm gonna do tomorrow, and the next day, and the next year, and the year after that. I'm shaking the dust of this crummy little town off my feet, and I'm going to see the world. Italy, Greece, the Parthenon, the Colosseum. Then, I'm coming back here and go to college and see what they know. And then, I'm going to build things. I'm gonna build airfields. I'm gonna build skyscrapers a hundred stories high. I'm gonna build bridges a mile long.
Those are some pretty high aspirations; George wants to have it all. He's oblivious to the fact that Mary is standing next to him, wanting something totally different—a life with George in Bedford Falls. We bet his big dreams are what make her love him, though.
POTTER: Forty-five. Forty-five. Out of which, after supporting your mother and paying your bills, you're able to keep, say, 10, if you skimp. A child or two comes along, and you won't even be able to save the 10. Now, if this young man of 28 was a common, ordinary yokel, I'd say he was doing fine. But George Bailey is not a common, ordinary yokel. He's an intelligent, smart, ambitious young man—who hates his job, who hates the Building and Loan almost as much as I do. A young man who's been dying to get out on his own ever since he was born. A young man ... the smartest one of the crowd, mind you, a young man who has to sit by and watch his friends go places because he's trapped. Yes, sir, trapped into frittering his life away playing nursemaid to a lot of garlic-eaters. Do I paint a correct picture, or do I exaggerate?
Mr. Potter has insight into George Bailey's deepest anxieties, and he hits him where it hurts most. He feeds George's doubts about himself and his disappointment in being stuck in Bedford Falls. Coming from someone else, this might be a sympathetic, supportive comment. But, this is Henry Potter, who really doesn't care about George at all. He just wants to take over his business.
GEORGE: It's this old house. I don't know why we don't all have pneumonia. Drafty old barn of a place. It's like growing up living in a refrigerator. Why do we have to live here in the first place and stay around this measly, crummy old town?
MARY: George, what's wrong?
GEORGE: Wrong? Everything. Why, you call this a happy family? Why do we have to have all these kids?
What's really bothering George is that Uncle Billy lost $8,000 of the Building and Loan's money, which could end up landing George in prison. But, his anxiety about this morphs into a kind of generalized dissatisfaction and anxiety about his life. All of his worries come bubbling to the surface. He even resents his children. George is just not himself.
POTTER: Look at you. You used to be so cocky! You were going to go out and conquer the world! You once called me a warped, frustrated old man. What are you but a warped, frustrated young man? A miserable little clerk crawling in here on your hands and knees and begging for help.
Potter twists the knife as George reaches his lowest point. Kicking a man when he's down is what he does best. He throws all of George's "failures" in his face.
CLARENCE (to himself): Hmm, this isn't going to be so easy. (to George) So, you still think killing yourself would make everyone feel happier, eh?
GEORGE (dejectedly): Oh, I don't know. I guess you're right. I suppose it would have been better if I'd never been born at all.
What George seems to be thinking here is that the world is dissatisfied with him, that everyone would have been happier without him around to muck things up. Clarence has his work cut out for him.
CLARENCE: What'd you say?
GEORGE: I said I wish I'd never been born.
CLARENCE: Oh, you mustn't say things like that. You … wait a minute. Wait a minute. That's an idea. (glances up toward heaven) What do you think? Yeah, that'll do it. All right. You've got your wish. You've never been born.
This is the turning point toward George realizing how unnecessary his discontent has been.