The Changeling, written by Christopher Judge, who plays Teal'c, is based on a famous 4th century BCE Chinese fable known as Zhuang Zhou Meng Die, meaning "Zhuangzi dreamed he was a butterfly."
Once Zhuangzi dreamt he was a butterfly, a butterfly flitting and fluttering around, happy with himself and doing as he pleased. He didn't know he was Zhuangzi. Suddenly he woke up and there he was, solid and unmistakable Zhuangzi. But he didn't know if he was Zhuangzi who had dreamt he was a butterfly, or a butterfly dreaming he was Zhuangzi.
This ancient fable was also the basis for the classic SF film, The Matrix. The writers and directors of the film, the Wachowski Brothers, are students of Eastern mysticism, including Zen and Daoism.
Morpheus: Have you ever had a dream, Neo, that you were so sure was real? What if you were unable to wake from that dream? How would you know the difference between the dream world and the real world?
This episode was not up to expectations. But that is a separate matter.