The First Doctor:The least important things, sometimes, my dear boy, lead to the greatest discoveries.
The Second Doctor:Well now I know you're mad, I just wanted to make sure.
The Third Doctor:Courage isn't just a matter of not being frightened, you know. It's being afraid and doing what you have to do anyway.
The Fourth Doctor:You're a classic example of the inverse ratio between the size of the mouth and the size of the brain.
The Fifth Doctor:An apple a day keeps the... Ah, never mind.
The Sixth Doctor:Planets come and go. Stars perish. Matter disperses, coalesces, forms into other patterns, other worlds. Nothing can be eternal.
The Seventh Doctor:Yes, that's right, you're going. You've been gone for ages. You're already gone. You're still here. You've just arrived. I haven't even met you yet. It all depends on who you are and how you look at it. Strange business, time.
The Eighth Doctor:I love humans. Always seeing patterns in things that aren't there.