Ein Traumspiel
During the 1890s he spent significant time abroad engaged in scientific experiments and studies of the occult. A series of apparent psychotic attacks between 1894 and 1896 (referred to as his ""Inferno" crisis") led to his hospitalization and return to Sweden. Under the influence of the ideas of Emanuel Swedenborg, he resolved after his recovery to become "the Zola of the Occult". In 1898 he returned to play-writing with "To Damascus", which, like "The Great Highway" (1909), is a dream-play of spiritual pilgrimage. His "A Dream Play" (1902) – with its radical attempt to dramatize the workings of the unconscious by means of an abolition of conventional dramatic time and space and the splitting, doubling, merging, and multiplication of its characters – was an important precursor to both expressionism and surrealism. He also returned to writing historical drama, the genre with which he had begun his play-writing career. He helped to run the Intimate Theatre from 1907, a small-scale theatre, modeled on Max Reinhardt's , that staged his chamber plays (such as "The Ghost Sonata").