- Helen Noel: Dr. Helen Noel, Captain. We've met...
- Helen Noel: [Kirk and Spock glance at each other. Without replying, Kirk joins her on the transporter pad] Don't you remember? The science lab Christmas party.
- Captain James T. Kirk: Yes, I remember.
- Helen Noel: You dropped in...
- Captain James T. Kirk: [cuttin her off] Yes, yes, I remember.
- Mr. Spock: Problem Captain?
- Captain James T. Kirk: [Kirk steps off the transporter pad to talk to Spock] Mr. Spock, you tell McCoy that she had better check out as the best assistant I ever had.
- Dr. Simon van Gelder: You smug, button-pushing brass hat! Wash your hands of it. Is that your system?
- Dr. McCoy: It's hard to believe that a man could die of loneliness.
- Captain James T. Kirk: Not when you've sat in that room.
- Dr. McCoy: I'm required to enter any reasonable doubts into my medical log; that requires you to answer in YOUR log. Sorry, Jim.
- Mr. Spock: What did he do to us?
- Dr. Simon van Gelder: He can reshape any mind he chooses. He used it to erase our memories, put his own thoughts there. He was surprised it took so much power. We fought him, remember? But we grew so tired. Our minds so blank, so open, that any thought he placed there became our thoughts. Our minds so empty, like a sponge needing thoughts, begging, empty. Loneliness. So lonely to be sitting there empty, wanting any word from him.
- Captain James T. Kirk: One of the advantages of being a captain, Doctor, is being able to ask for advice without necessarily having to take it.
- Captain James T. Kirk: Bones, are you aware that in the last 20 years, Dr. Adams has done more to revolutionise, to humanise prisons and the treatment of prisoners than all the rest of humanity have done in 40 centuries? I've been to those penal colonies since they begun following his methods, and they're not cages any more.
- Dr. McCoy: Jim...
- Captain James T. Kirk: They're clean, decent hospitals for sick minds.
- Dr. Tristan Adams: [toasting] To all mankind, may we never find space so vast, planets so cold, heart and mind so empty that... that we cannot fill them with love and warmth.
- Mr. Spock: Enterprise log, first officer Spock acting captain. I must now use an ancient Vulcan technique to probe into van Gelder's tortured mind.
- Mr. Spock: [performing a mind meld] You begin to feel a strange euphoria... your body floats...
- Dr. Simon van Gelder: Yes... I began to feel it.
- Mr. Spock: Open your mind; we move together... our minds sharing the same thoughts...
- Captain James T. Kirk: Can you imagine a mind emptied by that thing, without even a tormentor for company?
- Therapist: You will forget all you have heard. To remember any portion of it, any word, will cause you pain, terrible pain, growing more terrible as you fight to remember.
- Captain James T. Kirk: Mega-voltage. Touch the wrong line and you're dead.
- Helen Noel: Anything's better than Adams' treatment room.
- [last lines]
- Captain James T. Kirk: Take us out of orbit, Mr. Spock. Warp factor one.
- Mr. Spock: Acknowledged, Captain. Warp factor one.
- [first lines]
- crewman Berkeley: Ready to beam down... Energize!