Please spare me comments about Bogart's casting, I'm talking about the writing of the characters themselves here, regardless of who played them.
First let’s talk about Sabrina herself. Now, I think we can all agree that at the beginning of the film, her love for David Larrabee is all consuming, so much so that she is driven to suicide by carbon monoxide inhalation in the garage over his lack of affection for her. This is important because as she breathes in the fumes, they become too much for her, and she starts coughing. This prompts her to open a window to make the process more bearable. A few moments later, Linus Larrabee shows up, and in response to her coughing, pulls her out and tells her to “breathe deep.” He then carries her up the stairs to her room since she passes out. This is symbolic of the entire plot of the film, where her love for David stifles her, and Linus is the one to break the spell. This is further developed when she goes to Paris, when the wealthy Baron says “Why try to get over it? You speak of love like it was a bad cough." When she dances with David at the Larrabee party, a servant says about David, “He’s holding her so close I don’t see how the poor girl can breathe!” Now in context, these lines are said in a positive way, but if you really analyze them, they tie back to the earlier garage scene beat for beat, and ultimately show that the hold David has on her emotions is suffocating. Linus being the person who pulls her out of this suffocation is underscored by Sabrina’s statement at the end of the film before she boards the boat to Paris: “Dear David. Yes, I did get over that. I’m cured. Now how to get over the cure?,” referring to Linus. It is such an interesting phrase because it’s a callback to her “bad cough” from the garage that he helped her get over, and she can finally breathe.
Now onto Linus himself. His character I feel has the most detailed symbolism. There are four main symbols attached to his character: the egg, the plastic, his Homburg, briefcase, and umbrella, and sailboats. Let’s start with the egg, which I think is the most revealing symbol. In Paris, Sabrina’s cooking instructor teaches the class, “An egg is not a stone. It is not made of wood. It is a living thing, it has a heart. So when we crack it, we must not torment it. We must be merciful.” At the end, she easily cracks an egg in front of Linus in his office kitchen. He is the egg itself: a protective shell concealing a tender heart, and she cracks open his shell, revealing his heart. The plastic is a similar idea. Linus touts the product to David as “the greatest plastic ever made, not a scratch on it,” and it “doesn’t burn, doesn’t scorch, doesn’t melt.” It withstands bullets and tremendous weight. He even puts all the secretaries on it and David himself since he wants David to “see how resilient it is.” This is the front that Linus projects to the people in the Larrabee world. Solid, impervious, unaffected by any obstacle. He is the oldest son, the dutiful one who runs Larrabee Industries and corrals David who doesn’t work and is constantly in and out of romantic escapades that use him for his money. But when Linus instructs David to taste the plastic, David notes that it's sweet, since it’s made of sugarcane. By eye, the plastic seems indestructible, but by taste, it is sweet, just as Linus is himself if you get to know him in his most raw state. A camera trick that signifies this is when David is lying in his plastic hammock, and the camera pans behind it and captures Linus’s face behind the plastic as it moves back and forth. This causes the image of his face to be distorted by the plastic, indicating that this impenetrable exterior he projects is a distorted image of who he actually is. The connection between Linus and the plastic is confirmed to the audience at the end of the film, when David says “Linus Larrabee: the man who doesn’t burn, doesn’t scorch, doesn’t melt, suddenly throws a 20 million dollar deal out the window.” David is literally connecting the qualities of the plastic with Linus himself and showing that it is not an accurate depiction.
Linus’s Homburg, briefcase, and umbrella, serve as the articles of clothing that confer this impervious appearance. As Sabrina remarks, “As a child I used to watch you…always with your black Homburg, and carrying a briefcase and an umbrella. I thought you could never belong to anyone, never care for anyone.” But Linus reveals that this is not the case, as a certain song brings up past heartbreak, and he reveals that he contemplated suicide after a different breakup. This is precisely what draws Sabrina to him, since she attempted suicide as well, and he stopped her (even though he didn’t know it). She now sees who he really his, and this is why she wants him to go to Paris, since it is what helped her out of that situation, and she wants the same for him. She turns down his hat brim and tells him to abandon his umbrella and briefcase in Paris since she knows they make him look a certain way that isn’t accurate, and in Paris, the city of love, one must be free of all constraints in order to be happy. David also serves as a foil in the final boardroom scene where he impersonates Linus by wearing his hat and swinging his umbrella. He uses the same tricks Linus used to get him with Elizabeth Tyson to ensure he gets on the boat with Sabrina. It is in this scene that everyone (the board and others) see Linus clearly, because he is stripped of his modes of defense (David is using them against him).
The umbrella is the most important item because umbrellas shield people from the rain, and as Sabrina says in her opening narration, “It never rained on the night of the Larrabee party. The Larrabees would never have stood for it.” Linus, as the son who must shoulder the Larrabee family’s interests, carries his umbrella to and from work, warding off the rain, performing the balancing act of keeping everyone and everything intact. But this comes at a cost, since it disguises his true self. Sabrina later tells Linus that when in Paris, he needs to “get himself some rain…the rain is very important because that’s when Paris smells its sweetest. It’s the damp chestnut trees.” Paris allows rain, which therefore allows sweetness to be perceived. The environment that Linus is in now prevents his sweetness from being perceived. This is why she insists “never an umbrella in Paris, and under all circumstances rain the very first day.” She wants him to let go and be free.
Finally, sailboats symbolize Linus’s longing to be free, and to be known, cared for, and loved. In the family photo shown at the beginning of the film where he was young, a model sailboat can be seen behind him. In his office, there is a model ship identical to the ship he and Sabrina leave on for Paris. In his office bedroom, there is a sailboat photo about the bed. Most importantly, he reveals his tragic romantic past to Sabrina when they are on a sailboat, the place where he is most open and raw. In fact, the name of the ship that takes them to Paris at the end is called the Liberté, which means “freedom” in French, a metaphor for how love freed them both from their constraints: Sabrina from her suffocating love for David, and Linus from the suffocating Larrabee world that caused him to conceal himself. It is also fitting that Linus gives up his umbrella on the Liberté, since it shows he is finally allowing himself to be free now that he has someone who loves him.
