El curso de la historia

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.
Now... they're all gone... all gone.
None of them... could understand. Not even... my little Susan... or Vicki. And as for Barbara and Chatterton... 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, Doctor Who 3x05 ~ The Massacre of St Bartholomew's Eve · Part 4, Bell of Doom