I literally cannot overstate how fascinating this book is. If you don't own it, and you train in *any* martial art, stop right now, and purchase this book! It's absolutely chock full of good advice for martial artist's. It wouldn't be an overstatement to call this a "Martial Arts Bible"... I highly recommend it!
Moving beyond specific martial arts, (and although tending to maintain a Japanese background, it's not restricted to this), the author has constructed a balanced philosophy for training. He asks questions that most of us have never seriously considered or thought through. If nothing else, this book will force you to reconsider your martial philosophy.