This is the concluding volume in sixteen years' work on Realms of Being, which encompasses Santayana's philosophy. His disbelief in the reality of the metaphysical world and his insistence on his belief that the spiritual world exists in the beauty of the material world is an accepted tenet of his credo. Inspiration -- idealism spring from nature. He confesses himself intellectually a materialist, aesthetically a humanist. The book is an integral interpretation of human experience, discipline of mind and soul towards the order he craves and demands. He studies the function of spirit, its internal economy. He is faithful to his belief in the fact of incarnation. Through its inherent nature, spirit "introduces us into the spheres of truth or of essence, detaching us from each thing with humility and humour, and attaching us to all things with justice charity and pure joy". Your market is clearly defined.