Some of the basic history, theory, and philosophy of jujitsu, along with an explanation of ki and how it's used is explained in this book. It outlines the circle theory, the use of ki as an essential element, the basic mechanics of jujitsu, how techniques should be practiced and executed, what attitude should be maintained, and how theory should be applied to the learning of techniques. It's true of jujitsu that what appears to be simple on the surface becomes more complex as one probes deeper. As one's knowledge increases, the serious student will find more than meets the casual eye.