W. B. Yeats spent a great deal of his life immersing himself in magical, mystical, and philosophic studies in order, as he claimed, to devise a personal system of thought "that would leave [his] ... imagination free to create as it chose and yet make all that it created, or could create, part of the one history, and that the soul's." He succeeded in developing a cohesive metaphysics, and one which is surprisingly original. While he set it down in a series of philosophical treatises culminating in A Vision, it is most clearly elaborated in his plays, which breathe life and meaning into the rather obscure statements of the treatises.

In this book, the author traces "the history of the soul" as it is developed in Yeats's plays. She elucidates the underlying system of thought in the drama and establishes its importance to the aim and execution of the plays by drawing attention to a few of the central themes, metaphors, and symbols through which it is developed.

The manuscript and the earliest published versions of the plays are indispensable to this study as they retain much of the abstract thought which Yeats eliminated from the later versions. Martin traces the development of the metaphors and images which gradually replaced Yeats's abstractions. In the process, she is able to uncover new meaning in the plays, as many subtle and obscure passages become clearly understandable.