DOCTOR: Oh, I can't understand it. I just can't understand it. Violence is totally alien to people on this planet.

IAN: Oh, well, people change, Doctor. New leader, different set of circumstances.

DOCTOR: No, no, no, my dear Chesterton, no. All the more reason for people on this planet to hate death and destruction. My dear boy, when I was here before, the, what, the total population amounted to, a handle of people. Merely a hundred.

IAN: Is that all?

DOCTOR: Yes, exactly. All the more reason for holding onto life. Peace, friendship, happiness. This means everything to the people here.