This paper is not primarily about Blake’s influence upon Yeats, though it is concerned about the question of influence and tries to suggest what influence Blake has upon Yeats. Rather, its main concern is about how Yeats wages “Mental Fight” with Blake, his “master,” in order to define himself. Indeed, the figure of Blake stands like a pair of bookends around the literary career of Yeats. But Yeats’s relationship with Blake was a constant warefare between a poetic odd couple. In fact, Yeats’s whole career might be compared to beating on a wall, which Blake managed to pass through like a ghost. According to Yeats, Blake failed to eliminate himself properly from his poems. Because he was “a man without a mask,” he could not efface his own presence from his work. In other words, he could not become an impersonal medium for the voices out of the spiritual world. To outwit Blake and, in effect, to stake out his own spiritual territory, Yeats rejects not only Blake but also, in a sense, that part of himself which he has created in the mythic image of Blake. As the result of it he can subvert Blake. Now for Yeats, a “master” is not someone he emulates. Or he does not embody the way one has hoped to embody the voice of the Immortal Blake; rather, a “master” was his opposite or contrary, someone against whom he struggles to define himself. Even after “The Symbolism of Poetry” Yeats was not prepared to look like Blake, “a man without a mask.”