The central theme of Yeats poems is Ireland, its history, contemporary public life, and folklore, as well as, Celtic folklore. He came to associate poetry with religious ideas and sentiments (Yeats 2, 1). He was interested in folktales as a part of an exploration of national heritage and Celtic identity. Yeats was fascinated with reincarnation, communication with the dead, mediums, spiritualism, supernatural systems, and oriental mysticism. He changed from suggestive, beautiful lyricism to tragic bitterness. (Yeats 1, 1). His early work tended towards romantic lushness and fantasy like quality, and eventually moved on to a more modern style (Yeats 2, 1).
William Butler Yeats was very devoted to writing. Early on in his career he studied William Blake's poem and Emanuel Swedenborg's writings and visionaries. In eighteen eighty-eight, "Fairy and Folk Tales of the Irish Peasantry" was published, which was a study he did with George Russell and Douglas Hyde (Yeats 1, 1).
He not only wrote poetry but was also very political. In eighteen eighty-six, he formed the Dublin Lodge of Heretic Society. Then in eighteen eighty-seven, he joined the Esoteric Section of the Theosophical Society, but later ended up resigning. A couple years later, in eighteen ninety-six, he reformed the Irish literary Society and the National Literary Society in Dublin.