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Modernism and postmodernism, two significant literary movements, were profoundly influenced by Flann O'Brien. Modernism, emerging in the early 20th century, challenged traditional literary norms, embracing experimentation and exploring fragmented realities. Postmodernism, which followed, took this further, questioning grand narratives and embracing playful irony. Flann O'Brien's works, blending these movements, left an indelible mark on Irish literature.