Fans of science fiction know that the mark of a superior story is its willingness to ask the Big Questions. You know, "what's the meaning of life?" and "what makes us human?" and that sort of thing. In this alarmingly comprehensive fan-made compilation of clips from Doctor Who (in chronological order, covering the entire run of the series from 1963 to 2008, and including at least one segment from an episode that was never broadcast), you'll see that the show was always willing to ask one of those Big Questions. Repeatedly.