Borges once claimed that the basic devices of all fantastic literature are only four in number: the work within the work, the contamination of reality by dream, the voyage in time, and the double.

For one of those gnostics, the visible universe was an illusion or (more precisely) a sophism. Mirrors and fatherhood are abominable because they multiply and disseminate that universe.

One of the schools of Tlön goes so far as to negate time: it reasons that the present is indefinite, that the future has no reality other than as a present hope, that the past has no reality other than as a present memory.