Data Stellare 2534.0: Arrivando su Ekos, Kirk scopre che lo storico John Gill ha violato la Prima Direttiva, interferendo con il normale sviluppo socioculturale del pianeta. Sceso con Spock, infatti, Kirk si ritrova in una società identica a quella della Germania nazista.

Eneg: Punishment becomes ineffective after a certain point. Men become insensitive. [T:11:40]

Kirk: Oh, Mr. Spock, the guard did a professional job on my back. I appreciate if you'd hurry.
Spock: Yes, of course, Captain. Do you realize that the aim will be forcily very crude?
Kirk: I... don't care if you hit the broad side of a barn. Just hurry.
Spock: Captain, why should I aim at such a structure?
Kirk: Never mind, Spock. Just... get on with the job. [T:16:34]

Spock: Captain, I'm beginning to understand why you Earthmen enjoy gambling. No matter how carefully one computes the odds of success, but there is still a certain exhilaration in the risk.
Kirk: Very good, Spock. We may make a human of you yet.
Spock: I hope not. [T:28:12]

John Gill: Even historians fail to learn from history... they repeat the same mistakes. [T:44:34]

Kirk: The problem with the Nazis wasn't simply that their leaders were the evil, psychotic men they were. But the main problem, I think was the leader principle.
McCoy: A man who holds that much power, even with the best intentions, just can't resist the urge to play God. [T:46:19]

McCoy: Absolute power corrupt absolutely. Darn clever, these Earthmen, wouldn't you say?
Spock: Yes. Earthmen like Rameses, Alexander, Caesar, Napoleon, Hitler, Lee Kuan. Your whole Earth history is made up of men seeking absolute power. [T:46:41]