Catherine Pozzi was born in Paris, France, to Dr. Samuel Jean de Pozzi, a pioneering gynecologist-surgeon and writer of Italian-Swiss descent, and his wealthy wife Thérèse Loth-Cazalis. She grew up in an cultured, upper-class environment among artists and writers who were friends of her family. She attended a private girl's school then continued her education at home with various tutors, among them an English governess, and became fluent in German. She began keeping a diary at age 11 and maintained it all her life. It often reveals her to be an ironic observer of the worldly society in which she lived. She went to Oxford University for a year, and then traveled in England and Italy. In 1907, at age 25, she married Édouard Bourdet, a stockbroker who became a popular playwright, with whom she had a son. A few years later, she contracted tuberculosis, which slowly killed her. She began studying history, philosophy, religion, mathematics, chemistry, and biology. She also studied the piano with Marie Jaëll, a former pupil of Franz Liszt. In 1918, at the age of 37, she earned her baccalauréat degree at Strasbourg. Among her friends were Rainer Maria Rilke, Anna de Noailles, and Colette. In 1920, she began a tumultuous relationship with the married Paul Valéry, which lasted eight years. During her lifetime, she only published under her own name two or three articles in Le Figaro and La Nouvelle Revue Française. The rest of her works, including one of her six poems and a fictionalized autobiography, Agnès (1927), were published anonymously. She also wrote an unfinished philosophical essay, Peau d’Ame (The Skin of the Soul). Her diaries and notebooks were bequeathed at her death to the Bibliothèque nationale de France on condition that they be held privately for 30 years. In the 1990s, the diaries were published as Journal: 1913–1934 and Journal de jeunesse: 1893–1906, sparking renewed interest in her work. Her published correspondence with Paul Valéry represents only a small portion of their letters.