SPOCK: Fascinating.

KIRK: Sensor readings?
SPOCK: A mechanical device of unknown properties. I read no life forms aboard.
KIRK: Analysis, Science Officer?
SPOCK: Obviously, it intends to intercept us. It has made several course changes corresponding with our own
SPOCK: Unclear whether it intends to attack or merely communicate with us.
KIRK: Thank you, Science Officer. Come to one eight one mark seven.

SPOCK: Wrong. His mind killed him.
MCCOY: Come on, Spock. If you’ve got the answer, tell us.
SPOCK: Physical reality is consistent with universal laws. Where the laws do not operate, there is no reality. All of this is unreal.
MCCOY: What do you mean unreal? I examined Chekov. He’s dead.
SPOCK: But you made your examination under conditions which we cannot trust. We judge reality by the response of our senses. Once we are convinced of the reality of a given situation, we abide by its rules. We judged the bullets to be solid, the guns to be real, therefore they can kill.
KIRK: Chekov is dead because he believed the bullets would kill him.
SPOCK: He may indeed be dead. We do not know.
KIRK: But we do know that the Melkotians created the situation. If we do not allow ourselves to believe that the bullets are real, they cannot kill us.
SPOCK: Exactly. I know the bullets are unreal, therefore they cannot harm me.
KIRK: We must all be as certain as you are, Mister Spock, to save our lives.
SPOCK: Precisely.
MCCOY: But that’s not possible. There’d always be some doubt.
SPOCK: The smallest doubt would be enough to kill you.
MCCOY: We’re just human beings, Spock. We don’t have that clockwork ticker in our head like you do. We can’t turn it on and off.
KIRK: We must. Spock, a Vulcan mind meld.

Live long and prosper