In the series Breathless, someone made a remark about "the dark side" (joining it, or something). The series was set in the 1960s England, before the first movie in the franchise Star Wars was released. I'm curious about whether the phrase was used at that time.
Google NGrams says that the phrase "the dark side" existed before Star Wars. At first, I assumed that it was used as a literal dark side, in the shadow of something, but one example was The Dark Side of Trial by Jury, which doesn't sound like an example of a literal dark side.
Rather surprisingly, onelook.com doesn't give many links for "dark side", with even Wiktionary deciding not to have an entry for the concept.
Was "the dark side" used metaphorically before Star Wars?