A Theory of Everything: An Integral Vision for Business, Politics, Science, and Spirituality is a book by Ken Wilber detailing his approach to building a conceptual model of the World that encompasses both its physical and spiritual dimensions. He posits a unified ground-of-everything he calls Spirit.
The book's first four chapters cover the physical and mental development of this unified ground. Then, in the rest of the book, he lays out what he feels are the practical applications of his philosophy to business, education, medicine, ecology, and war. Beliefnet.com says that this book is, "Wilber's shortest, simplest overview of his work."