- Dr. McCoy: Well, we can't keep referring to her as 'she' as if she weren't here.
- Captain James T. Kirk: D'you have any ideas?
- Dr. McCoy: Well, I don't know about you, but I'm going to call her Gem.
- Dr. McCoy: Gem, Doctor?
- Dr. McCoy: Well, that's better than 'Hey, you'.
- Captain James T. Kirk: The best defense is a strong offense, and I intend to start offending right now.
- Dr. McCoy: Men weren't intended to live this far underground. It's just not natural.
- Captain James T. Kirk: And space travel is?
- Mr. Spock: Some men spend the majority of their lives in mines beneath the surface.
- Dr. McCoy: I'm a doctor, not a coal miner.
- Captain James T. Kirk: [to the Vians] You don't understand what it is to live. Love and compassion are dead in you. You're nothing but intellect!
- Dr. McCoy: Well, personally, I find it fascinating that with all their scientific knowledge and advances, that it was good old-fashioned human emotion that they valued the most.
- Scott: Perhaps the Vulcans should hear about this.
- Captain James T. Kirk: Mr. Spock, can you be prevailed upon to bring them the news?
- Mr. Spock: Possibly, Captain.
- Mr. Spock: [with a wry look] I shall certainly give the thought all the consideration it is due.
- Mr. Spock: [after McCoy injects him with hypospray] Your action is highly unethical. My decision... stands.
- [He collapses]
- Mr. Spock: What is puzzling you, Captain?
- Captain James T. Kirk: I'm not puzzled, Mr. Spock, I'm awed.
- Dr. McCoy: I'm with you, Captain. She awed me.
- Captain James T. Kirk: Be careful.
- Dr. McCoy: Why, she seems harmless enough.
- Mr. Spock: The sand-bats of Manark IV appear to be inanimate rock crystal, Doctor, until they attack.
- Captain James T. Kirk: If my death is to have any meaning, at least tell me what I'm dying for.
- Thann: If you live, you will have your answer.
- Lal: You are called "Captain." You are responsible for the lives of your crew. Is this correct?
- Captain James T. Kirk: It is.
- Thann: We find it necessary to have the cooperation of one of your men in our efforts.
- Captain James T. Kirk: We will NOT cooperate.
- Lal: When we resume our interrogations, you will decide which of your men we shall use. It is essential. There is an 87% chance that the doctor will die, and while Commander Spock's life is not in danger, the possibility is 93% that he will suffer brain damage resulting in permanent insanity.
- Dr. McCoy: I'm still Chief Medical Officer of the Enterprise. I'll tell you what you need and when you need it.
- Captain James T. Kirk: A race of mutes, like the civilization on Gamma-Vertis IV.
- Dr. McCoy: That's my observation, for whatever it's worth.