William Butler Yeats, born 1865 and died 1939. Yeats is one of the greatest poets known of the twentieth century. Also a philosophical person, Yeats had developed his own philosophy which states: “Yeats developed a philosophy that combined his interest in history, art, personality and society. His fundamental insight was that, in all these fields, conflicting forces are at work. In history, for example, when one type of civilization grows and eventually dies, an opposite type of civilization arises and takes its place. Likewise, human personalities can be defined as opposites: the creative or subjective person versus the active or objective person. (Literature by Prentice Hall [page 1144 Philosophy of Yeats]). That said, Yeats believed that if you believed there was such a thing as a “soul” not only would you live a life of concentric circles, but in fact there would be this thing we call an “afterlife.” So, explaining Yeats' philosophy, it means that we will be reborn depending on whether or not one of you wants to live life, or as he states in Sailing to Byzantium, live the new life as a monument. The critic Richard Ellmann claims that Yeats's poetry is based on the opposition between "the world of change" and a world of "immutability". Evidence of this is supported in Yeats' poetry, When You Are Old, The Lake Isle of Innisfree, The Wild Swans at Coole, The Second Coming and finally Sailing to Byzantium. All five of these poems represent change and stability in each poem; however, the change may vary depending on nature and civilization. In the first text, one of Yeats' poems, When You Are Old, demonstrates a change in the physical appearance of civilization. An example is as follows: “When you are old and gray and sleepy, and nodding by the fire, take this book, and read slowly, and dream of the sweet look your eyes once had, and their deep shadows; " (Prentice Hall Literature [page 1140 lines 1-4]). When You Are Old, by Yeats, describes how a once young man grew old and lost his beauty. As described in the text, one thing that changes is the appearance physical face of a human being. In relation to today's society we begin to devise "cures" to prevent aging, even if we are essentially dragging a decaying body around waiting for our soul to free itself, we find ways to prevent it all gives way and crumples..