Kirk: Mister Spock.
Kirk: There’s really something I don’t understand about all of this. Maybe you can explain it to me. Logically, of course. When you jettisoned the fuel and ignited it, you knew there was virtually no chance of it being seen, yet you did it anyhow. That would seem to me to be an act of desperation.
Spock: Quite correct, Captain.
Kirk: Now we all know, and I’m sure the doctor will agree with me, that desperation is a highly emotional state of mind. How does your well-known logic explain that?
Spock: Quite simply, Captain. I examined the problem from all angles, and it was plainly hopeless. Logic informed me that under the circumstances, the only possible action would have to be one of desperation. Logical decision, logically arrived at.
Kirk: I see. You mean you reasoned that it was time for an emotional outburst.
Spock: Well, I wouldn’t put it in exactly those terms, Captain, but those are essentially the facts.
Kirk: You’re not going to admit that for the first time in your life, you committed a purely human emotional act?
Spock: No, sir.
Kirk: Mister Spock, you’re a stubborn man.
Spock: Yes, sir.
Star Trek – Season 1: Episode 13 – “The Galileo Seven”