Ockultadagboken (The occult diary) is a diary kept intermittently for 12 years by the Swedish author and playwright August Strindberg (1849−1912). It comprises more than 300 folio leaves, from the first written in Paris in 1896 to the last entry from Stockholm in 1908. When Strindberg began the diary, his intention was to record characters and incidents that, although seemingly trivial, appeared to him to be significant, as well as strange coincidences, dreams, clairvoyant experiences, Bible quotations, and extracts from other books, usually without any comment. He gradually began to include items of a type more commensurate with that of a documentary diary: social and professional contacts, comments on day-to-day occurrences, references to books that he had read, and so forth. He pasted into the pages of the diary newspaper clippings that had caught his attention, and which often dealt with supernatural occurrences and experiences as well as with public events that interested him. The diary is an important source for any study of the composition of Strindberg’s works during the years he kept it, including the autobiographical novel written in French entitled Inferno (1896−97), the dramatic trilogy Till Damaskus (To Damascus, 1898−1904), and the play Spöksonaten (The ghost sonata, 1907).