A paracosm is a detailed imaginary world created inside one's mind. This fantasy world may involve humans, animals, and things that exist in reality; or it may also contain entities that are entirely imaginary, alien, and otherwordly. Commonly having its own geography, history, and language, the experience of such a paracosm is often developed during childhood and continues over a long period of time: months or even years.
Origin and usage
The concept was first described by a researcher for the BBC, Robert Silvey, with later research by British psychiatrist Stephen A. MacKeith, and British psychologist David Cohen. The term "paracosm" was coined by Ben Vincent, a participant in Silvey's 1976 study and a self-professed paracosmist. 
Psychiatrists Delmont Morrison and Shirley Morrison mention paracosms and "paracosmic fantasy" in their book Memories of Loss and Dreams of Perfection, in the context of people who have suffered the death of a loved one or some other tragedy in childhood. For such people, paracosms function as a way of processing and understanding their early loss. They cite James M. Barrie, Isak Dinesen and Emily Brontë as examples of people who created paracosms after the deaths of family members. Literary historian Joetta Harty connects paracosm play with imperialism in her writings on the Brontes, Thomas De Quincey and Hartley Coleridge. Dorothy and Jerome Singer reference paracosms in their studies on childhood imagination.
Marjorie Taylor is another child development psychologist who explores paracosms as part of a study on imaginary friends. In Adam Gopnik's essay, "Bumping Into Mr. Ravioli", he consults his sister, a child psychologist, about his three-year-old daughter's imaginary friend. He is introduced to Taylor's ideas and told that children invent paracosms as a way of orienting themselves in reality.
Paracosms are also mentioned in articles about types of childhood creativity and problem-solving. Some scholars believe paracosm play indicates high intelligence. A Michigan State University study revealed that many MacArthur Fellows Program recipients had paracosms as children. Paracosm play is recognized as one of the indicators of a high level of creativity, which educators now realize is as important as intelligence. In an article in the International Handbook on Giftedness, Michelle Root-Bernstein writes about paracosm play as an indicator of high levels of intelligence and creativity, which may "supplement objective measures of intellectual giftedness ... as well as subjective measures of superior technical talent." There is also a chapter on paracosm play in the 2013 textbook Children, Childhood and Cultural Heritage, written by Christine Alexander. She sees it, along with independent writing, as attempts by children to create agency for themselves.
Examples of paracosms include:
- K.C. Remington has written over twenty books in the Webbster and Button Children's Stories series, set in a paracosm called the Big Green Woods. 
- Middle Earth, the highly detailed fantasy world created by J.R.R. Tolkien, as expressed in his novels The Lord of the Rings and The Hobbit, as well as a sizable body of writings published posthumously containing fictional histories, languages and other reference material. Tolkien had been inventing languages since his teen years, only later imagining the people who spoke them or their environment.
- Gondal, Angria, and Gaaldine, the fantasy kingdoms created and written about in childhood by Emily, Anne, and Charlotte Brontë, and their brother Branwell, and maintained well into adulthood.
- Hartley Coleridge, created and maintained the land of Ejuxria all his life.
- Austin Tappan Wright's Islandia began as a childhood paracosm.
- M.A.R. Barker began developing Tekumel at age ten.
- Borovnia, the fantasy kingdom created by Juliet Hulme and Pauline Parker in their mid-teens, as portrayed in the film Heavenly Creatures.
- The modern fantasy author Steph Swainston's world of the Fourlands is another example of an early childhood paracosm.
- Henry Darger began writing about the Realms of the Unreal in his late teens and continued to write and illustrate it for decades.
- Joanne Greenberg created a paracosm called Iria as a young girl, and described it to Frieda Fromm-Reichmann while hospitalized at Chestnut Lodge. Fromm-Reichmann wrote about it in an article for the American Journal of Psychiatry; Greenberg wrote about it as the Kingdom of Yr in her novel I Never Promised You a Rose Garden.
- As children, novelist C. S. Lewis and his brother Warren together created a paracosm called Boxen which was in turn a combination of their respective private paracosms Animal-Land and India. Lewis later drew upon Animal-Land to create the fantasy land of Narnia, which he wrote about in The Chronicles of Narnia.
- Fantasy prone personality
- Fantasy (psychology)
- Fantasy world
- Imaginary world
- The Paracosm: a special form of fantasy, in Morrison, D.C. (Ed.), Organizing Early Experience: Imagination and cognition in Childhood. New York: Baywood, 1998.
- David Cohen and Stephen MacKeith, The Development of Imagination: The Private Worlds of Childhood (Concepts in Developmental Psychology). Routledge, 1992.
- Christine Alexander, "Playing the author: children's creative writing, paracosms and the construction of family magazines." In Kate Darian-Smith, Carla Pascoe (eds.), Children, Childhood and Cultural Heritage. Routledge, 2013.
- Morrison, Delmont C. and Shirley L., Memories of Loss and Dreams of Perfection: Unsuccessful Childhood Grieving and Adult Creativity. Baywood, 2005. ISBN 0-89503-309-7.
- Joetta Harty, The islanders: Mapping paracosms in the early writing of Hartley Coleridge, Thomas Malkin, Thomas De Quincey, and the Brontes. Dissertation, George Washington University. published Feb. 2008.
- Singer, Dorothy and Jerome Singer, The House of Make-Believe: Children's Play and the Developing Imagination. Harvard University Press, 1992. ISBN 0-674-40875-6.
- Taylor, Marjorie, Imaginary Companions and the Children Who Create Them . Oxford University Press, 2001. ISBN 0-19-514629-8.
- Gopnik, Adam, "Bumping Into Mr. Ravioli: A Theory of Busyness, and Its Hero". In The Best American Magazine Writing 2003, ed. by the American Society of Magazine Editors (Harper Perennial, 2003), p. 251. Originally appeared in the New Yorker September 30, 2002, and also found in Gopnik's collection of autobiographical essays, Through the Children's Gate: A Home in New York (Vintage Canada, 2007). ISBN 1-4000-7575-0.
- Po Bronson and Ashley Merrin, The Creativity Crisis. In Newsweek, 2010-07-10, page found 2010-08-20.
- Root-Bernstein, Michelle, "Imaginary Worldplay as an Indicator of Creative Giftedness". In the International Handbook on Giftedness, ed. by Larissa Shavinina. Springer, 2009.
- K.C. Remington, profile at Smashwords e-book site, with a bibliography.
- Humphrey Carpenter, Tolkien: A Biography. Houghton-Mifflin, June 1977.
- Emily Brontë, Gondal Poems. 1973 by Folcroft Library Editions.
- Emily Brontë, Gondal's Queen, A Novel in Verse. Edited by Fannie Ratchford. University of Texas Press, 1955.
- Fannie Elizabeth Ratchford, Legends of Angria. New Haven: Yale University Press, 1933.
- Fannie Elizabeth Ratchford, The Brontes' Web of Childhood. Columbia University Press, 1941.
- Andrew Keanie, Hartley Coleridge: A Reassessment of His Life and Work. Palgrave Macmillan, 2008.
- The Fourth World, detailed website about the film and the actual people and events.
- Dangerous Offspring: An Interview with Steph Swainston. Clarkesworld Magazine, October 2007.
- Fromm-Reichmann, Frieda, "Psychotherapy of Schizophrenia". Am J Psychiatry 111:410-418, December 1954.
- Greenberg, Joanne, I Never Promised You a Rose Garden. ISBN 0-8124-1588-4.
- Lewis, Clive Staples, "Surprised By Joy: The Shape of My Early Life." Harcourt Brace & Company, 1956. ISBN 0-15-687011-8.
- Francis Jacox, Ejuxria and Gombroon: Glimpses of Day-Dreamland. 1871 essay discusses many paracosms created by people who later became writers, although he never uses the word.
- Elizabeth Knox, Origins, Authority, and Imaginary Games discusses the creative process as paracosms evolve into adulthood.
- Sarah Knox, Identity, Inclination and Imaginary Games is a response to Elizabeth's essay.
- Blog about Paracosm on DailyKos