"You are the Companion. He is the man. You are two different things."
One of Shatner's best delivered orations on the nature of the human condition and human relationships. Kirk's attempt to reason with the Companion was compelling and effective. Shatner's earnest performance sold the truth of his message perfectly as usual.
KIRK: Companion, do you love the man?
COMPANION: I do not understand.
KIRK: Is he important to you, more important than anything? Is he as though he were a part of you?
COMPANION: He is part of me. The man must continue.
KIRK: He will not continue. He will cease to exist. By your feeling for him, you are condemning him to an existence he will find unbearable. He will cease to exist.
COMPANION: He does not age. He remains forever.
KIRK: You speak of his body. I speak of his spirit. Companion, inside the shelter, a female of our species is dying. She will not continue. That is what will happen to the man unless you release all of us.
COMPANION: I do not understand.
KIRK: Our species can only survive if we have obstacles to overcome. You take away all obstacles. Without them to strengthen us, we will weaken and die. You regard the man only as a toy. You amuse yourself with him.
COMPANION: You are wrong. The man is the center of all things. I care for him.
KIRK: But you can't really love him. You haven't the slightest knowledge of love, the total union of two people. You are the Companion. He is the man. You are two different things. You can't join. You can't love. You may keep him here forever, but you will always be separate, apart from him.
COMPANION: If I were human there can be love?
That the Companion was willing to sacrifice its natural form in the hope of a chance for love with Cochran demonstrated that Kirk's message was effective at defining what love between humans actually means and just how important it is to us all.