DOCTOR: But the final responsibility is mine, and mine alone. Listen, 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?

DOCTOR: Just touch these two strands together and the Daleks are finished. Have I that right?

DOCTOR: Davros, if you had created a virus in your laboratory, something contagious and infectious that killed on contact, a virus that would destroy all other forms of life, would you allow its use?

DAVROS: It is an interesting conjecture.

DOCTOR: Would you do it?

DAVROS: The only living thing, a microscopic organism reigning supreme. A fascinating idea.

DOCTOR: But would you do it?

DAVROS: Yes. Yes. To hold in my hand a capsule that contains such power, to know that life and death on such a scale was my choice. To know that the tiny pressure on my thumb, enough to break the glass, would end everything. Yes, I would do it! That power would set me up above the gods. And through the Daleks, I shall have that power!

(In another corridor they come across guards in protective gear.)

DOCTOR: Excuse me, can you help me? I'm a spy.

(And he bangs their heads together.)