Maria van Rysselberghe (Brussels, 1866 - Cabris, Alpes maritimes, 1959) is one of the most fascinating "secret" writers of all time, a short-lived cult author whose legend has seduced many readers over the years . Daughter of a cultured family linked to the world of Belgian art, and married to the painter Théo van Rysselberghe, she was also the closest friend of André Gide, who named her "Petite Dame" because of her small stature and physical presence. From 1918 he undertook the task of recording every day and until the death of Gide (1951) all that he witnessed in the life of the writer: phrases, events, the environment in which he lived, the genesis of his works , his attitude towards the events of his time, his intimate life ... For a third of a century he filled nineteen thick notebooks of "Notes for the authentic history of André Gide". Today this chronicle is known as The Notebooks of the Petite Dame and, published by the publisher Gallimard, is an irreplaceable document for the knowledge of an entire era of French literature and, in general, European. But his work is not exclusively composed of these notebooks: animated by Gide, he wrote, at least, two fundamental texts, translated by Errata naturae: For a nightingale and Forty years ago.