William Butler Yeats was an #Irish poet and #playwright. He also was the leader of the Celtic Revival Movement and the founder of the Abbey Theatre. His writing style was #romanticism in the early career, then changed to the modernism because of the experience of participation in political movements. He was awarded the #Nobel Prize in Literature in 1923, and was the one of the most important figures of literary in the 20th century. He wrote a poem "When You Are Old" to Maud Gonne, that was his most famous works.