POPPINS: The die is cast. I'm a lily!
GRANDPA VANDERHOF: Have some popcorn.
Poppins decides to become one of Grandpa's dreamers. The reference is to the lilies of the field, which Biblically do not sow or reap, but are cared for by God. Dreamers don't worry where their next meal is coming from—though the truth is that Poppins' toys seem like they could maybe make him some money, if he wanted to sell them. But of course he doesn't need to because Grandpa has an infinite supply of money, for some mystical reason. Infinite supplies of mystical money make dreaming a lot easier.
TONY: We can't just pop out of the building with no place to go. Very bad idea that, you know. I know two people that did that once—they went out of the building, they were uncertain, so they just walked and walked and walked and finally they just died... of hunger. Now you wouldn't want anything like that to happen... because if, if that happened... you're so beautiful.
You Can't Take It With You is into dreaming. But the film also endorses impulsive goofiness and setting off without figuring out where you're going to dinner. The film sees dreamers as folks without plans, perhaps. Tony here is maybe parodying his father a little; Mr. Kirby would never set out for dinner without knowing where he's going (though, as Tony shows later, deliberately showing up on the wrong night for dinner to thwart your sweetie's plans can have some disastrous consequences).
TONY: It takes courage. You know everybody's afraid to live.
ALICE: You ought to hear Grandpa on that subject. You know he says most people nowadays are run by fear. Fear of what they eat, fear of what they drink, fear of their jobs, their future, fear of their health. They're scared to save money, and they're scared to spend it. You know what his pet aversion is? The people who commercialize on fear, you know they scare you to death so they can sell you something you don't need.
Alice's advice here (taken from Grandpa) seems like a variation on Franklin Roosevelt's famous comment that "there is nothing to fear but fear itself." Was Roosevelt right? The fact that Tony and Alice are talking about people "nowadays" is important. The film was released in 1938, during the Great Depression.
People were very afraid of taking risks then, and with reason; there were few jobs, and making a living was extremely difficult. In You Can't Take It With You, the only thing keeping you from your dreams is fear. But that's not exactly always true in the real world, outside the film.
GRANDPA VANDERHOFF: How's Essie doing?
KOLENKHOV: Confidentially, she stinks.
GRANDPA VANDERHOFF: Oh well, as long as she's happy.
Essie isn't actually a good dancer, but she likes dancing, and dreaming of being a dancer. That's good enough for Grandpa.
GRANDPA VANDERHOF: [offering grace] Quiet, please, quiet! Well, sir, here we are again. We've had quite a time of it lately, but it seems that the worst of it is over. Course, the fireworks all blew up, but we can't very well blame that on you. Anyway, everything's turned out fine, as it usually does. Alice is going to marry Tony; Mr. Kirby, who's turned out to be a very good egg, sold us back our house—he'll probably forget all about big deals for a while. Nobody on our block has to move and, with the right handling, I think we can even thaw out Mrs. Kirby here. We've all got our health; as far as anything else is concerned, we still leave that up to you. Thank you. Bring it on, Rheba!
The conclusion of the film is Grandpa offering up a prayer, in which he basically says he's not going to plan anything and will leave it all up to God. You can pursue your dreams because God will take care of you. Which is a comforting thought, and works in the film, anyway.
BILL HUGHES: What happened? You were all right last time I saw you.
GRANDPA VANDERHOFF: One of my granddaughters dared me to slide down the banister.
BLAKELY: Too bad, is it serious?
GRANDPA VANDERHOFF: No, just a sprain or something. The thing I like most about it is the crutches, I've been wanting to walk on them ever since I was a kid. Haven't you?
Grandpa hurt his ankle because he was playing with Alice. Family can get you in trouble—but also lead you to happy surprises, like Grandpa getting his crutches. In this film, at least, family never leads you astray.
GRANDPA VANDERHOF: Right up to the very last, she couldn't walk into a room without my heart going thump, thump, thump.
Grandpa's relationship with his departed wife ties together the themes of romantic love and family in the story. Grandpa keeps the house because it's where Grandma lived, so even though she's gone, their romantic love provides the foundation for the family. And that love is mirrored in Alice and Tony (Alice is supposed to look just like Grandma, according to Grandpa.)
GRANDPA VANDERHOFF: Do you have any Russian stamps for me?
KOLENKHOV: No, nobody writes to me anymore. They are all dead.
Kolenkhov's family back in Russia is all dead—but he's got a new family with Grandpa and the Sycamores. Again, family is defined by who you love and/or hang out with, rather than by where and to whom you were born.
TONY: I want them to meet you as you are, not some trumped up evening with everybody acting unnaturally.
Tony is more than a little in love with Alice's family, presumably because they're so much more fun to be around than the grumpy Mr. Kirby. He seems to have hoped that they would win over his own family—though it didn't really work out.
MR. KIRBY: Mr. Vanderhof, you once told me I was a failure as a father.
GRANDPA VANDERHOF: Oh, I didn't mean that.
MR. KIRBY: I know, but I am.
It's ultimately family that transforms Mr. Kirby— both Grandpa's family, and his concern about his own son Tony. Family, at least in I Can't Take It With You, makes you a better person.
MR. KIRBY: Boys like Tony don't marry stenographers.
Mr. Kirby is supposed to be wrong here, obviously; the message of the film is that there is no class barrier to love. But he's also somewhat accurate. Alice isn't exactly a stenographer; she's working as a secretary, but does she really need the job? She quits without worrying about where her next meal is coming from; her family has resources. She's not actually the class Mr. Kirby thinks she is, which is perhaps why he doesn't recognize the danger of marriage is real.
TONY: You know, there never was anything in my life that I couldn't get if I didn't scream loud enough.
TONY: Yeah, and I've had plenty of practice with it since I was a baby. I'm pretty terrific at it now. Here, let me show you a little example.
[Tony screams, and the office boy opens the door. Tony screams again and the office boy leaves. Tony and Alice laugh.]
Tony is incredibly charming and fun (he's Jimmy Stewart, after all!) But he's also spoiled. The film mostly focuses on getting Mr. Kirby to be a better person, but Tony has some improving to do as well (under the tutelage of the Sycamores, of course.)
TONY: I can feel a scream coming on right now... it's up here, in my throat! It's fighting to get out!
ALICE: No, please, don't scream!
HEAD WAITER: [comes over to the table] What happened?
TONY: What happened? Well, there was a mouse!
HENRY: A mouse? In this place?
TONY: What do you mean, "mouse"? It was a rat, this long, and it had hair on it! And there were six or seven of them!
This scene is all about tweaking upper-class society. Alice and Tony are in a lavish dining room, which they end up scampishly disrupting. The tweaking of the upper class, though, depends on the fact that Alice and Tony are upper-classish themselves; they don't need to worry about being arrested, for instance. If you want to take on the upper class, it's best to have some money and connections yourself.
MRS. KIRBY: She's probably from some dull middle class family; as soon as Tony sees us all together he'll realize how impossible it is.
The joke here is that Alice's family isn't dull at all—and not exactly middle-class either. Also, the family's difference is exactly what attracts Tony to them; he's sick of bankers, and wants to find something a little more exciting (something with harmonicas.)
ALICE: [to the Kirby family] The next time you want to go slumming, stay away from our neighborhood!
Alice is defending her family and their neighbors, who are all gathered in the courtroom. It's the common people vs. the snooty bankers—a sentiment that must have resonated during the Great Depression, when there was (as now) great inequality.
TAX COLLECTOR: Our records show you have never paid an income tax.
GRANDPA: That's right
TAX COLLECTOR: Why not?
GRANDPA: I don't believe in it
This is perhaps the most famous scene in the film—and it involves Grandpa hoarding money. Grandpa isn't willing to pay his back taxes, because he says the government does nothing for him, or anyone. One thing the government did during the Depression, though, was pay unemployment, and invest in works programs to get people jobs.
The tax collector doesn't mention any of this though, and so you don't get to hear whether Grandpa thinks it's worth paying tax money for those programs. The truth, though, is that the rabidly anti-tax stance Grandpa takes would make more sense coming from Mr. Kirby; Grandpa is supposed to love community and democracy.
Perhaps that's why Capra undermined the scene at the end, with a throw-off line about how Grandpa doesn't really owe any money. The scene as it stands didn't quite make sense for the film version, so the filmmakers tweaked it.
GRANDPA VANDERHOF: Well now suppose I won't sell them my place, what're they going to do?
NEIGHBOR: That's right, you own your place.
GRANDPA VANDERHOF: Sure I do.
NEIGHBOR: And they're going to need it too, won't they?
GRANDPA VANDERHOF: You bet they will, and it'll take more than money to make me sell my property. Now go on back to work, stop cluttering up the street, we'll all be arrested.
It's true that you can't take it with you, but while you're here, owning your own home can be very useful. Grandpa's (moderate) wealth is a huge boon to his friends. It's odd that later he just sells the house though he knows this will destroy the entire neighborhood. Why didn't he sell it to someone other than Mr. Kirby, if he had to sell? But perhaps Capra didn't think things through; that sometimes happens in the movies.
GRANDPA VANDERHOF: Maybe it'll stop you trying to be so desperate about making more money than you can ever use? You can't take it with you, Mr. Kirby. So what good is it? As near as I can see, the only thing you can take with you is the love of your friends.
That's the title and the theme, right there. Friends, not love. Write it down, live it. And, you know, if things get tough, ask your friends for money (as Grandpa does.)
GRANDPA VANDERHOF: What if all your deals fall through? Might be a good thing for you.
MR. KIRBY: Man, you're crazy.
GRANDPA VANDERHOF Well, maybe I am, but I used to be just like you once. Then one morning, when I was going up in the elevator... it struck me I wasn't having any fun. So I came right down and never went back. Yes, sir. That was thirty-five years ago.
Grandpa was going up in that elevator towards wealth and more wealth… and then he came down, got out of the rat race, and started collecting stamps. The moral is, push the elevator button for love, not money. (Or something like that.)
GRANDPA VANDERHOF: Scum, are we? What makes you think you're such a superior human being? Your money? If you do, you're a dull-witted fool, Mr. Kirby. And a poor one at that. You're poorer than any of these people you call scum, because I'll guarantee at least they've got some friends. While you with your jungle and your long claws, as you call 'em, you'll wind up your miserable existence without anything you can call friend. You may be a high mogul to yourself, Mr. Kirby, but to me you're a failure—failure as a man, failure as a human being, even a failure as a father. When your time comes, I doubt if a single tear will be shed over you. The world will probably cry, "Good riddance." That's a nice prospect, Mr. Kirby. I hope you'll enjoy it. I hope you'll get some comfort out of all this coin you've been sweating over then!
Grandpa gets uncharacteristically riled up and gives Mr. Kirby what for. The "long claws" here reference Social Darwinism—the belief that the rich got rich by being the fittest, and that society is a struggle to see who comes out on top. Grandpa is rejecting that idea; the goal isn't to be the biggest lion in the jungle, but to have the most friends (lion or otherwise.)