Spirituality and mysticism in Yeats's poetry?

Yeats’s devotion to mysticism led to the development of a unique spiritual and philosophical system that emphasized the role of fate and historical determinism, or the belief that events have been preordained. Yeats had rejected Christianity early in his life, but his lifelong study of mythology, Theosophy, spiritualism, philosophy, and the occult demonstrate his profound interest in the divine and how it interacts with humanity. Over the course of his life, he created a complex system of spirituality, using the image of interlocking gyres (similar to spiral cones) to map out the development and reincarnation of the soul. Yeats believed that history was determined by fate and that fate revealed its plan in moments when the human and divine interact. A tone of historically determined inevitability permeates his poems, particularly in descriptions of situations of human and divine interaction. The divine takes on many forms in Yeats’s poetry, sometimes literally (“Leda and the Swan” [1923]), sometimes abstractly (“The Second Coming” [1919]). In other poems, the divine is only gestured to (as in the sense of the divine in the Byzantine mosaics in “Sailing to Byzantium” [1926]). No matter what shape it takes, the divine signals the role of fate in determining the course of history.