"One day, I shall come back. Yes, I shall come back. Until then, there must be no regrets, no tears, no anxieties. Just go forward in all your belief, and prove to me I am not mistaken in mine."
-William Hartnell, the First Doctor, The Dalek Invasion of Earth, 1964.
This has to be one of the most heart-warming and tear-inducing scene in the history of ever.