McCoy: Do you know why you’re not afraid to die, Spock? You’re more afraid of living. Each day you stay alive is just one more day you might slip and let your human half peek out. That’s it, isn’t it? Insecurity. Why, you wouldn’t know what to do with a genuine, warm, decent feeling.
Spock: Really, Doctor?
McCoy: [pause] I know. I’m worried about Jim, too.
(Star Trek TOS, 2x25 “Bread and Circuses”)
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