In ‘Creative Writers and Day-Dreaming’ [1907], Freud asks:

Might we not say that every child at play behaves like a creative writer, in that he creates a world of his own, or rather, rearranges the things of his world in a new way which pleases him? It would be wrong to think he does not take that world seriously; on the contrary, he takes his play very seriously and he expends large amounts of emotion on it. The opposite of play is not what is serious but what is real. (Freud 1990, pp.131-2)

Writing is a serious game: playing with language, voice and form, it day-dreams worlds into words.

References:

Sigmund Freud, ‘Creative Writers and Day-Dreaming’, The Penguin Freud Library Vol. 14: Art and Literature, trans. by James Strachey (London: Penguin, 1990)