(after McCoy's successful surgery restoring Spock's brain)
Kirk: How do you feel, Spock?
Spock: On the whole Captain, I believe I'm quite fit. It's fascinating! A remarkable example of a retrograde civilization at the peak, advanced beyond any of our capabilities and now operating at this primitive level which you saw. And it all began thousands of years ago when a glacial age reoccurred. You see, this underground complex was developed for the women. Men remained above. And male/female schism took place. A fascinating cultural development of a kind...
McCoy: I knew it was wrong, I shouldn't have done it!
Kirk: What's that?
McCoy: I should have never reconnected his mouth!
Kirk: Well, we took the risk, Doctor.