"My dear Steven, history sometimes gives us a terrible shock, and that is because we don’t quite fully understand. Why should we? After all, we’re too small to realize its final pattern. Therefore don’t try and judge it from where you stand. I was right to do as I did. Yes, that I firmly believe.
Steven… Even after all this time, he cannot understand. I dare not change the course of history. Well, at least I taught him to take some precautions; he did remember to look at the scanner before he opened the doors. And now, they’re all gone. All gone. None of them could understand. Not even my little Susan. Or Vicki. And as for Barbara and…Chesterton - they were all too impatient to get back to their own time. And now, Steven. Perhaps I should go home. Back to my own planet. But I can’t… I can’t…"
- The Doctor, The Massacre, Episode 4: Bell of Doom
(February 26 1966)
Written by Donald Tosh & John Lucarotti