Paul Sédir (born Yvon Le Loup; 2 January 1871 - 3 February 1926) was a French author, professor, banker, and mystic noted for his extensive work on esotericism and Christian mysticism. A student of Gérard Anaclet Vincent Encausse, better known as Papus, founder of the Martinist Order, into which Sédir was initiated. Sédir's first text, Les Miroirs Magiques (Magic Mirrors), was published in 1894 by Lucien Chamuel. This work, along with others like Les Tempéraments et la Culture psychique (1894), Les Incantations (1897), and La Médecine occulte (1900), reflects his profound knowledge in various domains of esotericism, including Kabbalah, astral light, and magical practices.

In this collection of two of Sédir's works, Austin Avison introduces Paul Sédir, situating him in the exciting period of societal and cultural changes during the pre-war years in Europe. Avison then offers a translation of Sédir's Dreams: Theories-Practice-Interpretation, a short discourse of how dreams function, their art, and a list of dream interpretations, and finally his translation of Magic Letters, which offers an insight into Sédir himself not only through his own prologue, but also in the collection of letters he curated for the collection. These two texts, along with Sédir's other contributions, marked a significant chapter in the development of French esotericism in the early 20th century.