The Doctor (Doctor Who) footage. Tom Baker did reappear, but as "the Curator", an ambiguously different character who he was not credited for playing. A voice actor, John Guilor, recorded a line of audio impersonating the First Doctor, for which he was credited as "Voice Over Artist". In other multi-Doctor stories, the multiple actors are all credited as "The Doctor", the exception being "The Three Doctors" (1972–73), which credited William Hartnell, Patrick Troughton and Jon Pertwee as "Doctor Who" as the 1972 serial preceded the practice of crediting the character as "The Doctor". In "Human Nature" (2007), the plot involves the Tenth Doctor altering
The Doctor (Doctor Who) it is revealed that he also left to investigate the mystery of why good prevails in a universe where evil would seem to have so many advantages. It would be during his twelfth incarnation that the Doctor realizes his actions made the difference in the balance between good and evil in the universe. In other media, more has been revealed of the Doctor's early life. In the Past Doctor Adventures novel "Divided Loyalties", the Doctor recalls his Academy years in a dream induced by the Celestial Toymaker. According to this, he was a member of an organisation called the Deca,