William James is to classical American philosophy as Plato was to Greek and Roman philosophy: an originating and inspirational fountainhead. Thinkers as diverse as C. S. Peirce, Josiah Royce, John Dewey and the late work of A. N. Whitehead took their point of departure from William James, especially his monumental Principles of Psychology. Influential philosophers elsewhere were also deeply influenced by James, for instance Henri Bergson, Edmund Husserl, Miguel de Unamuno, and Ludwig Wittgenstein.

With the completed publication of all of James's writings, including his manuscripts and notebooks, the full range and philosophical virtuosity of his work comes into focus. For too long the thought of William James was taken to be novel and intriguing but lacking in technical sophistication. In reading James the first response is one of elation at the apparent simplicity and obvious elegance of the literary style. After several careful...