[1][2] The origin of the term is attributed to fragment B89 (Diels–Kranz numbering) of the pre-Socratic philosopher Heraclitus:[1][2] "The waking have one common world, but the sleeping turn aside each into a world of his own.
"[3] The term has various interpretations: idios kosmos is associated with dreaming, imagination, and delusion; koinos kosmos with wakefulness, reason, and consensus reality.
[1][2][4] From the 1950s, the term was adopted by phenomenological/existential psychologists, such as Ludwig Binswanger and Rollo May, to refer to the experience of people with delusions or other problems who have trouble seeing beyond a limited private world of their own minds or who confuse this private world with shared reality.
[4][5][6][7] It was an important part of novelist Philip K. Dick's views on schizophrenia, as expressed in his 1964 essay "Schizophrenia & 'The Book of Changes'", where he drew on his familiarity with the existential psychologists, Heraclitus, and the I Ching.
[8][9][10] The koinos kosmos is mentioned in the Dick novel Lies Inc. where the protagonist mentions that he was "able to maintain contact with the stable objective koinos kosmos so that I never forgot that what I was seeing emanated from my own psyche".