The Doctor: "If someone who knew the future, pointed out a child to you and told you that that child would grow up totally evil, to be a ruthless dictator who would destroy millions of lives... could you then kill that child?"
Sarah Jane: "We're talking about the Daleks. The most evil creatures ever invented. You must destroy them. You must complete your mission for the Time Lords!"
The Doctor : "Do I have the right? Simply touch one wire against the other and that's it. The Daleks cease to exist. Hundreds of millions of people, thousands of generations can live without fear... in peace, and never even know the word 'Dalek'."
Sarah Jane: "Then why wait? If it was a disease or some sort of bacteria you were destroying, you wouldn't hesitate."
The Doctor : "But if I...wipe out a whole intelligent life form, then I become like them. I'd be no better than the Daleks."
Genesis of the Daleks, Part 6
(April 12th 1975)
Written by Terry Nation