Yeats`s chronologically penultimate play Purgatory in his posthumous Collected Plays of W. B. Yeats is difficult to put into a pigeon-hole. It is neither a traditional one like Cathleen ni Houlihan nor a No-type one like The Death of Cuchulain. which ends the book. In Last Poems arid Two Plays, the last book W. B. Yeats was preparing to publish just before his death, Purgatory occupies the last seat. The actual last play The Death of Cuchulain precedes it. Considering Yeats`s concerns in reordering his works when he published books the place of the play betrays a significance hard to overlook. Purgatory is a rather simple play, the shortest among the published plays he has ever written, with only two characters, an old man and his young son, on a simple symbolic set. The old man is a ``Yeatsian`` believer of ``re-living`` or ``dreaming-back`` after one dies a violent or passionate death. The old man kills his son in order to eliminate the ``re-living`` process of his dead mother. But his double murder (50 years ago he killed his father who violated the ``big house`` tradition) brings no deliverance from ``re-living`` for his dead mother because she cannot get rid of her human ``lust.`` Lust-life we find in Crazy Jane poems and other last poems manifests itself at the end of the play. The last work in Yeats`s ``last`` book shows us eloquently that the final choice he reached is filthy life over deliverance from life`s filth.