Important Archetypes of Dualism

Double-Thought: such as transience, paradox, dichotomy, juxtaposition

Double-Mind: such as schizophrenia or bi-polar disorder, or a Jekyl and Hyde mentality

Double-City: a city that surrealistically exists even beneath the surface of a puddle, this is depicted well and poetically in the book Pile: Petals from St. Klyde's Computer.

Double-World: a world that exists on axes which represent opposing qualities of the world, nature, politics, magic, or ideologies. This is often called The Antipodes, after an expression by Aristotle; similar expressions are gamut, axiom, apogee, and stricture.

Double-Universe: such as depicted by the Yin-Yang represents duality at every level.