- Kara: Brain and brain! What is *brain*? It is Controller, is it not?
- Dr. McCoy: Yes. Yes, in a way, it is. The human brain controls the individual's functions.
- Captain James T. Kirk: [with dawning realization] Bones... Scotty... Spock's... brain... controls.
- Captain James T. Kirk: [regarding Spock] You've got him on complete life support. Was he dead?
- Dr. McCoy: He was worse than dead.
- Captain James T. Kirk: What do you mean?
- Dr. McCoy: Jim...
- Captain James T. Kirk: Come on, Bones, what's the mystery?
- Dr. McCoy: His brain is gone.
- Captain James T. Kirk: We came to put you back. Where are you?
- Mr. Spock: [voice] Back where?
- Captain James T. Kirk: Back into your body. We brought it along with us.
- Mr. Spock: [voice] Thoughtful, Captain, but probably impractical. While I might trust the Doctor to remove a splinter, or lance a boil, I do not believe he has the knowledge to restore a brain.
- [last lines]
- [McCoy has restored Spock's brain]
- Captain James T. Kirk: How do you feel, Spock?
- Mr. Spock: On the whole, Captain, I believe I am quite fit. It's fascinating. A remarkable example of a retrograde civilization. At the peak, advanced beyond any of our capabilities, and now operating at this primitive level which you saw. And it all began thousands of years ago, when a glacial age reoccurred. You see, this underground complex was developed for the women. The men remained above, and a male-female schism took place. A fascinating cultural development of a kind which has...
- Dr. McCoy: I knew it was wrong. I shouldn't have done it.
- Captain James T. Kirk: What's that?
- Dr. McCoy: I should have never reconnected his mouth.
- Captain James T. Kirk: Well, we took the risk, Doctor.
- Mr. Spock: [unfazed by the interruption] As I was saying, a fascinating cultural development of the kind which hasn't been seen in ages. The last such occurrence took place on old Earth, when the Romans were warring...
- [Kirk, McCoy and Scotty are in an elevator that descends abruptly]
- Dr. McCoy: Call Chekov and tell him to send my stomach down!
- Dr. McCoy: Vulcan physiology limits what I can do. Spock's body is much more dependent on that tremendous brain for life support.
- Captain James T. Kirk: Then we'll have to take him with us.
- Dr. McCoy: Take him... take him where?
- Captain James T. Kirk: In search of his brain, Doctor.
- Dr. McCoy: Where are you going to look for Spock's brain? How're you gonna find it?
- Captain James T. Kirk: I'll find it.
- Dr. McCoy: Even if you do, I can't restore it. I don't have the medical technique.
- Captain James T. Kirk: It was taken out. It can be put back in.
- Dr. McCoy: But I don't know how!
- Captain James T. Kirk: The thief that took it has the knowledge. I'll FORCE it out of her!
- Captain James T. Kirk: Show us the three Class M planets, Mr. Chekov.
- Chekov: The one on the left, number 3, it rates letter B on the industrial scale.
- Captain James T. Kirk: Earth equivalent approximately... 1485.
- Chekov: Yes, sir. Second planet Class M, number 4, rates letter G.
- Captain James T. Kirk: The year 2030.
- Sulu: But that ship, Captain, either was many years ahead of us, or it was the most incredible design fluke in history.
- Captain James T. Kirk: Third Class M planet, Mr. Chekov?
- Chekov: Number 6. No sign of industrial development. At last report, in a glacial age. Sapient life plentiful, but on a most primitive level.
- Captain James T. Kirk: Now, as I understand it, Mr. Chekov, there are three Class M planets...
- Chekov: Yes, sir.
- Captain James T. Kirk: ...not one of which is capable of launching an interstellar flight...
- Chekov: No, sir.
- Captain James T. Kirk: ...yet one of them accomplished it.
- Chekov: Yes, sir.
- Captain James T. Kirk: Thank you, Mr. Chekov.
- Creature: You... are not the Others?
- Captain James T. Kirk: No. We come from a far place. We are men.
- Creature: Men?
- Captain James T. Kirk: Like yourselves.
- Creature: You are small. Like the Others.
- Captain James T. Kirk: Who are the Others?
- Creature: The givers of pain... and delight.
- Captain James T. Kirk: A dead and buried city... on a planet in a glacial age.
- Chekov: And the male humanoid who doesn't know the meaning of the word "female".
- Scott: "Pain and delight", he said up above.
- Dr. McCoy: I'm sure you noticed the 'delight'-aspect of this place.
- Captain James T. Kirk: Yes, I certainly did notice those delightful aspects.
- Captain James T. Kirk: This fellow is keeping us from our property.
- Scott: Well, isn't there a way to correct that situation?
- Captain James T. Kirk: I certainly think that science might provide an answer.
- Dr. McCoy: It does, Captain.
- Captain James T. Kirk: Agreed, Doctor.
- [they take on the guards in a surprise attack]
- Mr. Spock: [voice] Captain, there is a definite pleasurable experience connected with the hearing of your voice.
- Captain James T. Kirk: Spock, you're in a black box tied in with light rays into a complex control panel.
- Mr. Spock: [voice] Fascinating.
- Captain James T. Kirk: You'll be without your Controller for the first time; but... you'll be much better off, I think.
- Kara: We will die!
- Captain James T. Kirk: No. You'll live, and develop, as you should have. All this shouldn't have been done for you. Now the women here below and the men here above will control together.
- Kara: They will not help us without the pain.
- Captain James T. Kirk: There are other ways. You'll discover them.
- Captain James T. Kirk: [Kirk and a landing party have beamed down to a planet in search of Spock's brain] Life form readings, Mr. Spock? -
- [realizes his mistake]
- Captain James T. Kirk: - Mr. Scott?
- Sulu: That ship, Captain, either was many years ahead of us, or it was the most incredible design fluke in history.
- Sulu: Ship's Log, Lieutenant Sulu recording. I am holding the Enterprise in orbit about planet Sigma Draconis VII. Captain Kirk's hunch that Spock's brain is on this planet appears to be correct. Ensign Chekov remains on the surface, to act as liaison between the Captain and the Enterprise.
- Captain James T. Kirk: From the very first, I appreciated your ability.
- Kara: Good, Captain Kirk. Then you will also appreciate that without the Teacher, I would not have the knowledge to use that which you have thoughtfully provided.
- [she suddenly produces a phaser and aims it at Kirk]
- Scott: That phaser is set to kill.
- Dr. McCoy: [after acquiring knowledge from the Teacher] Of course. Of course. A child could do it. A child could do it.
- Scott: Captain, that power we picked up above - we're gettin' closer.
- Captain James T. Kirk: A lot of it?
- Scott: Enough to push this planet out of orbit.
- Captain James T. Kirk: What source?
- Scott: Either a nuclear pile a hundred miles across or...
- Captain James T. Kirk: Or what?
- Scott: Ion power.
- Mr. Spock: [voice] I seem to have a body which stretches into infinity.
- Scott: Body? Why, ya have *none*.
- Mr. Spock: Then, what am I?
- Dr. McCoy: You are a disembodied brain.
- Mr. Spock: Fascinating. It could explain much, Doctor. My medulla oblongata is hard at work apparently breathing, apparently pumping blood, apparently maintaining a normal physiologic temperature.
- Captain James T. Kirk: Readout, Mr. Chekov.
- Chekov: No structures, Captain. No mechanized objects that I can read, no surface consumption, no generation of energy. Atmosphere is perfectly all right, of course. Temperature, a high maximum of 40 - livable.
- Captain James T. Kirk: [regarding Chekov] You have a thick skin.