"Niebla (Nivola)" by Miguel de Unamuno is a novel written in 1907 and published in 1914. It follows Augusto Pérez, a wealthy young law graduate and only son of a widowed mother, as he navigates romantic troubles and existential crises. When Augusto questions his daily existence and visits Unamuno himself, the author reveals a shocking truth: Augusto is merely a fictional being. This innovative work challenges the boundaries between reality and fiction, exploring the nature of existence itself.