Star Trek: Voyager1995

Commander Chakotay:
Every culture has its demons. They embody the darkest emotions of its people. Giving them physical form in heroic literature is a way of exploring those feelings. The Vok'sha of Rakella Prime believe that hate is a beast which lives inside the stomach. Their greatest mythical hero is a man who ate stones for 23 days to kill the beast, and became a saint.

Lieutenant Tuvok:
Such fables are necessary only in cultures which unduly emphasize emotional behavior. I would point out there are no demons in Vulcan literature.

Commander Chakotay:
That might account for its popularity.