This book explores the question of Yeats’s identity as an important issue in the criticism of the Irish poet. The identity of the poet with the advent of postcolonial theory into Irish studies in general and Yeats’s studies in particular, this controversial issue has gained new dimensions. Whether Yeats was a revolutionary and anti-colonial nationalist or a poet with unionist and colonialist inclinations has been the subject of much debate and less agreement. One can justify any of these versions of Yeats by concentrating on some of his works and utterances and ignoring some others. However, this will result in an incomplete and partial picture of a complex, multidimensional, and ever-changing poet such as Yeats. It explores the different aspects of W. B. Yeats’s poetic theory and political ideology. It also studies Yeats’s modernity and influences on his contemporaries as well as successors, such as T. S. Eliot, Ezra Pound and W. B. Aden. Though three common themes in Yeats’ poetry are love, Irish nationalism and mysticism, modernism is the overriding theme in his writings. Yeats started his long literary career as a romantic poet and gradually evolved into a modernist poet. As a typical modern poet, he regrets the post-war modern world, which is now in disorder and chaotic tuition and laments the past.