"It's a robot. Ash is a goddamn robot."
This quote is uttered by Parker when he realizes that Ash is not a human, as previously believed. His disbelief and frustration are understandable. In the scene, Ash has tried to choke Ridley to death after she confronts him for his motives (or programming, as it were). Parker beheads him, revealing circuitry and robotics where there ought to be flesh and bones. This raises deep questions about what unknown threats the crew face, given that a robot has been programmed to be willing to kill crew members in order to safeguard the alien. Parker's fear and indignant response to the revelation of Ash's android status reflects this.
"You still don't understand what you're dealing with, do you? The perfect organism. Its structural perfection is matched only by its hostility...I admire its purity. A survivor...unclouded by conscience, remorse, or delusions of morality."
Here, Ash's reanimated but disembodied head expresses his admiration for the cold-blooding killing machine of an alien. He outlines the purity of the creature, and labels it the "perfect organism." Ash's criteria for perfection are entirely scientific, but they also have philosophical significance as well, and serve as a convincing argument about what constitutes a "human." Ash posits that the most beautiful aspect of any organism is its efficiency as predator, free from what he perceives to be the impositions of morality, conscience, and remorse. The monster's ability to survive against all odds, and its lack of human morality, make it perfect in Ash's eyes. It is also significant that Ash believes the human beings' morality to be a set of mere "delusions"; in the eyes of the robot, achieving morality is impossible, fruitless, and pointless, amounting to nothing more than a hollow "delusion."
"Ash, that transmission. Mother's deciphered part of it. It doesn't look like an S.O.S...it looks like a warning."
Ripley says this to Dallas from the cockpit of the Nostromo, as she realizes that they followed a transmission that they need not have followed. Ripley's realization serves as a bit of foreshadowing for the horrors to come, especially since three crew members are currently aboard the alien craft on the stormy planetoid that took them out of their way. The quote sets in motion a powerful irony, in which the crew who tries to be helpful to a signal they think is expressing need discover that it is they who are in desperate need of rescue, having mistakenly followed a signal into a fatal trap.
"Final report of the commercial starship Nostromo, third officer reporting. The other members of the crew, Kane, Lambert, Parker, Brett, Ash and Captain Dallas, are dead...This is Ripley, last survivor of the Nostromo, signing off."
This quote comprises Ripley's final log entry as the film ends and she makes her way back towards Earth in the escape shuttle, having killed the alien. While Ash had admired the alien for ability to survive, Ripley wins out in the end and becomes the "last survivor of the Nostromo." This quote represents a bit of hope at the end of a terrifying journey. Ripley is matter-of-fact and straight-forward in her entry, but underneath this formality, there is a great deal of hope and a profound sense of relief.
"What's the matter? The food ain't that bad..."
Parker, the comic relief of the ship, often wise-cracking and laughing, says this to Kane when he sees Kane beginning to choke at the group meal. It is clear that Kane is having an intense physical response, and we will soon discover that Kane's choking has little to do with the food, and more to do with the vicious alien birthing itself from his chest. Parker's attempt at a joke strikes an ominous chord as the viewer realizes that the stakes are far more dire than simply an upset stomach.
Ash: Ripley, for God's sake, this is the first time that we've encountered a species like this. It has to go back. All sorts of tests have to be made.
Ellen Ripley: Ash, are you kidding? This thing bled acid. Who knows what it's gonna do when it's dead?
Ash: I think it's safe to assume it isn't a zombie.
In this quote, Ash and Ripley argue over the dangers of what appears to be the remains of the deceased alien. Ash has already undermined Ripley's authority by letting Kane into the ship without being properly quarantined, and here he seeks to undermine her judgment again by insisting that they bring the alien back to Earth. Ripley rightfully thinks that alien is a threat to their safety, even if he is in fact dead. Ash, however, retorts teasingly that the alien is fully dead and is not a zombie that is at risk of coming back to life.
"That's the only way. We'll move in pairs. We'll go step by step and cut off every bulkhead and every vent until we have it cornered. And then we'll blow it the fuck out into space! Is that acceptable to you?"
At this point, Dallas, Brett, and Kane have all died, and Ripley takes the role of captain. Left with the excitable Parker, frantic Lambert, and passively silent Ash, Ripley has no choice but to become strong-willed and instructive. Here, she outlines her plan for getting rid of the alien: they will corner it and then send it flying into space. Seeing the ways that the group has begun to fragment, she takes it upon herself to give detailed instructions. We see in this quote Ripley's ability to take charge and use forceful language to fortify her doubtful team. She becomes a hard-nosed and toughened captain, and will not accept any ambivalence or unhelpful emotionality from her companions.
"It's got a wonderful defense mechanism. You don't dare kill it."
When they puncture one of the claws of the facehugger that has attached itself to Kane's face, a strange acidic yellow fluid pours out, burning through the floor of the infirmary and dripping down several levels. Clearly the blood-like substance is damaging and toxic, and Parker notes just how dangerous the substance, and what an asset its toxicity is to its survival. If they were to try and kill the alien, he suggests, they would expose themselves to the deadly burning poison.
Ripley: Did you ever ship out with Ash before?
Dallas: I went out five times with another science officer. They replaced him two days before we left Thedus with Ash. Hmm?
Ripley: I don't trust him.
Dallas: Well, I don't trust anybody.
After Ash insists that they keep the remains of the seemingly dead alien on the ship with them (and Dallas hesitantly agrees), Ripley confronts Dallas in private, and insists that she does not trust Ash, asking Dallas if he has ever worked with him before. Dallas insists that he had worked with a different science officer in the past and that Ash was a late addition to the expedition. Ripley responds that she doesn't trust Ash, and Dallas seems to agree, but it doesn't matter much, as Dallas tells her, he doesn't trust anybody. While Ripley takes her distrust of Ash seriously, Dallas takes the hardheaded perspective that no one is trustworthy, so they might as well just listen to Ash and continue on their journey.
Lambert: Look, could you open the god-damned hatch? We have to get him inside.
Ripley: No. I can't do that and if you were in my position, you'd do the same.
Dallas: Ripley, this is an order. Open that hatch right now, do you hear me?
Ripley: Yes.
Dallas: Ripley. This is an order. Do you hear me?
Ripley: Yes. I read you. The answer is negative.
After Kane is attacked by the creature on the planetoid, Dallas and Lambert are eager to reenter the ship, but Ripley insists that she cannot let them in, as it is standard procedure to quarantine all of them for 24 hours before letting them back on. Lambert, who has already established herself as a complainer, becomes impatient and demands that Ripley let them in, but Ripley assures her that she must do what is called for by protocol. Dallas, in spite of not having the authority to do so, orders Ripley to let them onto the ship, but Ripley remains firm. Even though she hears their desires to come on the ship, she is determined to do what is right, and remain loyal to safety precautions that are meant to ensure the best outcome for all.
