The Doctor and Wilfred in “The End of Time”

[bluntly] I'm going to die.

Well, so am I one day.

Don't you dare!

Alright, I'll try not to! [chuckles]

But I was told: "He will knock four times". That was the prophecy: knock four times and then...

Yeah, but I thought, when I saw you before, your people could change like your whole body...

I can still die. If I'm killed before regeneration, then I'm dead. Even then, even if I change, it feels like dying. Everything I am dies. Some new man goes sauntering away... and I'm dead.