J.R.R. Tolkien called the creation of a secondary fictional world “sub-creation.”
Tolkien developed this idea most explicitly in his 1939 lecture “On Fairy-Stories,” later published in essay form. He argued that a writer can construct a coherent Secondary World with its own internal laws, history, languages, and stories. A reader can then experience “secondary belief” while inside that imagined world.
The prefix “sub-” reflects Tolkien’s theological understanding of human creativity. In his view, people do not create from nothing in the same way God creates the primary world; instead, they exercise a derived creative power by reshaping and recombining elements of reality.
Tolkien’s invented languages, genealogies, calendars, maps, and legends illustrate this method. The concept is broader than merely inventing a fantasy setting. It describes the disciplined process of making an imagined world feel internally true, consistent, and independent of the author’s immediate explanation.