"If they hang you I'll always remember you."
Sam says this to Brigid after he discovers that she is the one who killed his partner, Miles. He tells her he is in love with her but can never trust her, and later, that he must honor the death of his partner. Thus he's ready to turn her over to the police, where she will either get a life sentence (the best case scenario is 20 years), or be executed. This quote shows Sam's brusque and matter-of-fact response to his own feelings, choosing what is right over whatever feelings of love he has for Brigid. His tone is at once straight-forward and somewhat ironic; while the thought of living on in someone's memory forever is romantic in a certain light, in this particular instance, it alludes to possible death by execution, a horrifying fate.
"When you're slapped you'll take it and like it."
Sam says this to Cairo in his apartment as the jumpy sidekick to Gutman keeps trying to strong-arm Sam, brandishing his gun wildly and threatening Sam. Sam retaliates with aggression and slaps Cairo in order to establish his power. In this quote, Sam is not only aggressing, but asserting his masculinity over Cairo, creating a disciplinary and punishing relation between the two. Sam wants Cairo to know that he is not to be toyed with, and asserts his dominance even further by implying that Cairo wants to be dominated.
"I am, I've always been a liar."
When Sam accuses Brigid of lying about the Maltese Falcon, Brigid admits this about herself. Having hedged on her knowledge about the Falcon's whereabouts, Miles' murder, and her connection to the deaths that have occurred since she arrived in town, Brigid becomes suddenly overcome with a kind of rueful grief. She is, she admits, a liar, and she always has been. Here she is obliquely alluding to her life of crime, expressing a strange combination of regret and self-awareness. Sam is the only person who can fully see through Brigid's femme fatale performances and get her to tell the straightforward truth.
Cairo: "You always have a smooth explanation ready."
Sam: "What do you want me to do, learn to stutter?"
In this interaction between Cairo and Sam, Cairo teases Sam about his ability to change his story, adapt to his circumstances, and talk smoothly. Sam wittily counters that the alternative to his "smooth explanation" would be adopting a stutter. Sam is an expert performer when it comes to deceiving his adversary, but he never affects a weakened or an inarticulate state, instead speaking clearly and smoothly. It is in this moment that we see Cairo and Sam as opposites of one another: Cairo is slippery and insinuating, affecting superciliousness, whereas Sam, even when he is lying, maintains his smooth and sturdy attitude.
“I am a man who likes talking to a man who likes to talk"
After asking Sam if he likes to talk—vetting him to see if he will be a willing and compliant interviewee—and Sam responding him that he does, Gutman makes this statement. While on the surface it simply means that Gutman is glad that Sam is willing to be cooperative, that he will be forthcoming and honest, it also shows that Gutman is a man who likes to speak in epigrams, always universalizing his individual experiences. To Gutman, Sam is one among many, he represents a certain kind of man. Furthermore, liking to talk, in Gutman's eyes, is a sign that someone will give him what he wants, and the statement carries a threatening meaning beneath it. One wonders what Gutman thinks about or does to a man who doesn't like to talk. Gutman's statement here is suggestively coercive.
Detective Tom Polhaus: "Heavy. What is it?"
Sam Spade: "The, uh, stuff that dreams are made of."
Detective Tom Polhaus: "Huh?"
These are the final lines of the film. As Tom picks up the counterfeit Maltese Falcon from the table and examines it, he notes its weight and asks Sam what it is. Enigmatically, Sam tells him that it's the "stuff dreams are made of." Sam, having gone through hell to capture the villains, understands the symbolic weight of the statuette, and understands that its perceived value is what began the whole slew of crimes in the first place. When Sam sends Effie to fetch the police, he tells her not to tell them about the statuette, so the police involvement in the case has nothing to do with the bird. The statuette is Sam's little secret with himself, and this quote reflects that. Tom doesn't understand what he means, but Sam doesn't tell him anything more before walking out. The Maltese Falcon is the unreachable dream, the symbol of everything a person wants but can never have.
"I couldn't be fonder of you if you were my own son. But, well, if you lose a son, it's possible to get another. There's only one Maltese Falcon."
This quote also reveals the importance of the Maltese Falcon. When Sam suggests that they make Wilmer their fall man and turn him into the police for all the murders, Gutman hesitates at first, citing his fondness for Wilmer, before finally agreeing. Gutman is more committed to the Maltese Falcon than anything else in his life. Indeed, he is willing to sacrifice one of his most loyal employees in order to have the statuette in his possession. This quote reveals Gutman's moral weakness, his willingness to do anything to procure his beloved bird.
"When a man's partner is killed, he's supposed to do something about it. It doesn't make any difference what you thought of him. He was your partner and you're supposed to do something about it. And it happens we're in the detective business. Well, when one of your organization gets killed, it's—it's bad business to let the killer get away with it, bad all around, bad for every detective everywhere."
After Sam tells Brigid he has to turn her into the police, and she begs him not to, he gives her this stern talking-to, which reveals both his commitment to his principles, and his inner conflict in betraying the woman he loves. He cannot let Brigid go unpunished, in spite of his affections, because that is not what a good detective is supposed to do. He tells her that his stance is not about any kind of personal affinity for Miles—Sam didn't even really like Miles—but that if he let the killer get away, it would be "bad business." Here, Sam expresses his loyalty to an abstract code of ethics, one which is tied primarily to his job and to his sense of duty. Indeed, he feels that by turning Brigid in, he is doing good "for every detective everywhere." It doesn't matter whether he feels love for her, a good detective does the right thing always, especially when it comes to honoring his business partner.
"You're a good man, sister."
After Sam enlists Effie's help in his convoluted exploits, after Captain Jacobi has arrived with the package containing the Maltese Falcon, he pinches her chin and says this line. It is a sweet moment in the film, as we see Sam exhibit genuine affection for someone and for once accept honest help. Sam's relationship with Effie is one of the only affectionate alliances he maintains; otherwise, he is the consummate loner. While Effie is simply a secretary, her years of working for Sam have made her a keen extra set of eyes, with the savviness of a junior detective. In this moment, Sam recognizes her helpfulness, in a tender, if somewhat condescending way.
"You do such wild and unpredictable things."
As Brigid realizes that Sam plans to turn her in to the authorities, she is horrified at first, but then—in this line—she mistakes his stated intentions for a lie or a joke. Earlier in the film, after Sam kisses her unexpectedly, Brigid noted that Sam is "wild and unpredictable," always one step ahead of everyone, and that one never knows what he is going to do next. This quote comes in a moment of terrified wishful thinking, echoing her sentiments from earlier in the film. She desperately hopes that Sam is yet again putting her on, lying through his teeth in order to manipulate her. However, Sam is not lying, and his intentions to turn her in to the police are real.