Barbara A. Suess 
Progress & Identity in the Plays of W.B. Yeats, 1892-1907 [PDF ebook] 

Progress and Identity in the Poems of W. B. Yeats explores the ways in which Yeats»s plays offer an alternative form of progress via a philosophical system of opposites: Always seeking the opposite, the nature of which changes as we change, we continually augment our personalities, and ultimately improve society, with the inclusion of the Other. This system, which eventually became Yeats»s doctrine of the mask, provided his contemporaries with a method of changing what science, Platonism, and Victorian bourgeois ideologies claimed to be inescapable qualities of self. Progress and Identityn relocates Yeats»sliterary, social, and political relevance from hisessentializing cultural nationalism to his later, morebroad-minded definitions of progress.