Yeats completed his theory of tragedy after his translation and the performance of Sophocles’ King Oedipus. The theory of his tragedy is as follows. First, the protagonist tries to overcome his fate and inquires into passionate identity. Second, the protagonist reaches tragic ecstasy. Thirdly, the protagonist changes his passion into wisdom. Fourthly, the protagonist completes the ultimate reality through the tragic gaiety. In short, Yeats, after completing tragic gaiety in Sophocles’ King Oedipus, shows how he embodies the ultimate reality.