Yeats’s studies of ancient myths, legends and occult tradition form a part of his artistic enterprise to quest for the occult wisdom and reaffirm the power of occult imagination. His work is so deeply immersed in the supernatural that it intends to regenerate the modern world by reopening ancient spiritual wellsprings and reviving primal religious sensibilities. His interest in occultism did most to create occult images and symbols as signs of imaginative salvation. Yeats’s mystical lore helped him ascertain the spiritual reality within human consciousness and use magical symbols as a means of calling up visions. Art for Yeats is about the “wisdom of the daemonic image” which holds for a moment of illumination the warring opposites of flesh and soul. Yeats created occult images of spiritual intensity to convey the quality of the Unity of Being out of the increasingly scientific and secular culture of the modern age. His occult images create the rich texture of his poetry that examines the spiritual situation of modern humanity.

Throughout Yeats's life, his occultism absorbed much of his time and energy. Yeats's occultism supported and enriched his poetry and plays, providing him with themes, the symbols, a philosophy that affirmed recurring self-renewal. Through the development of Yeats's occult thinking, from the Golden Dawn, through Per Amica Silentia Lunae, to A Vision, a continuous, coherent direction can be traced. Books II and III of A Vision, deal with the nature of the human soul, its different principles, and its progression after death. In "The Completed Symbol," Yeats elaborates on the Four Principles of the soul ― the Husk, the Passionate Body, the Spirit, and the Celestial Body. The Principles find their Unity in the Celestial Body, man's archetype in Heaven. In "The Soul in Judgement", examining the six after-death states, death, in general, is also presented as a transfer of consciousness from the physical plane to a higher one. During the first three states, or until Beatitude, the Spirit passes each time into a higher state of consciousness; after Beatitude, following the circular pattern of "The Great Wheel," the Spirit lapses slowly into relative unconsciousness. These six states, like the twenty-eight phases, affect each other, and in each one the Spirit has to act under certain laws. The soul has to pass through all of these states in order to progress and to prepare for its reentry into the physical world. This belief in the six after-death states stems from the occult sources mainly Theosophy which also teaches that the soul passes through six planes of consciousness after death -- the divine, the monadic, the spiritual, the intuitional, the mental, and the astral plane or plane of passions and emotions. Yeats uses the lunar cycle to explain the soul's journey between lives. The concept of the Thirteenth Sphere is important because in the occult traditions, the number thirteen is also symbolic of unity and perfection. In A Vision the Thirteenth Sphere represents Unity since in it all antinomies are resolved. Yeats's view of the soul is directly related to his belief in a universal duality ― the existence of opposite but equal forces that dominate a cycle alternately.

Yeats's poetry and writings were a display of his passion for mysticism and the occult. This view on Yeats has been largely expressed in various publications. Many of Yeats's critics, including Ellmann, agree that the roots of Yeats's system are in Theosophy. The roots of Yeats's philosophy are in Theosophy, being a comprehensive, unifying systems of all occult tradition, and the first metaphysical system that Yeats encountered. Being faced with the dilemma between faith and disbelief, Yeats contacted numerous texts on the subject occultism and met Blavatsky, the founder of Theosophy society, claimed to have the ability to offer a "synthesis" of religion, science, and philosophy. After many metaphysical conversations with her and many hours of long thought on the issue, Yeats took one of his first steps on his path of occult wisdom. Yeats's fascination with occultism and mysticism was so profound, and his need to create a unifying mythology so great, that he decided to develop an esoteric system of his own. Thus, between 1917 and 1925, Yeats had written A Vision, an elaborate, complicated system that is of importance in understanding Yeats's works. The first version, published in 1925, was later revised, and final version was published in 1937. In Book IV and V of A Vision Yeats had expounded the notion that history moves in great two-thousand-year cycles. This circle represents the moon and the twenty-eight phases of the moon which are closely related to the progression of time and world history. Yeats suggested all things are subject to a cycle of changes, which can be regarded as bi-polar, passing from a state of objectivity to one of subjectivity before returning to objectivity again. In this view he was strongly influenced by the Theosophists, especially Blavatsky and the Kabbalists, who saw the law of periodicity as one of the fundamental and absolute laws of the universe. Yeats believed that history was cyclic and that every 2,000 years a new cycle begins, which is the opposite of the cycle that has preceded it. In his poem "The Second Coming," the birth of Christ begins one cycle, which ends, as the poem ends, with a "rough beast," mysterious and menacing, who "slouches towards Bethlehem to be born." Yeats's theory of the historical cycle is directly related to his belief in a universal duality -- the existence of opposite but equal forces that dominate a cycle alternately. This view is in accordance with the occult traditions which teach that the First Cause exhibits periodically different aspects of itself. Yeats believed that kingdoms rise movement of history is an hour within the day of a large movement, and that all these cycles are caught within one all-inclusive "Great Year" which has a cosmic purpose. The Kabbalah says the alternation between judgement and mercy must be on equal terms. The germ finally goes back to its root principle, the Unity out of which everything proceeds.