Third is the Fire book. This book is about fighting. The spirit of fire is fierce, whether the fire be small or big; and so it is with battles. The Way of battles is the same for man to man fights and for ten thousand a side battles. You must appreciate that spirit can become big or small. What is big is easy to perceive: what is small is difficult to perceive. In short, it is difficult for large numbers of men to change position, so their movements can be easily predicted. An individual can easily change his mind, so his movements are difficult to predict. You must appreciate this. The essence of this book is that you must train day and night in order to make quick decisions. In strategy it is necessary to treat training as part of normal life with your spirit unchanging. Thus combat in battle is described in the Fire book.

Fourthly the Wind book. This book is not concerned with my Ichi school but with other schools of strategy. By Wind I mean old traditions, present-day traditions, and family traditions of strategy. Thus I clearly explain the strategies of the world. This is tradition. It is difficult to know yourself if you do not know others. To all Ways there are side-tracks. If you study a Way daily, and your spirit diverges, you may think you are obeying a good Way but objectively it is not the true Way. If you are following the true way and diverge a little, this will later become a large divergence. You must realize this. Other strategies have come to be thought of as mere sword-fencing, and it is not unreasonable that this should be so. The benefit of my strategy, although it includes sword-fencing, lies in a separate principle. I have explained what is commonly meant by strategy in other schools in the Tradition (Wind) book.

Fifthly, the book of the Void. By void I mean that which has no beginning and no end. Attaining this principle means not attaining the principle. The Way of strategy is the Way of nature. When you appreciate the power of nature, knowing rhythm of any situation, you will be able to hit the enemy naturally and strike naturally. All this is the Way of the Void. I intend to show how to follow the true Way according to nature in the book of the Void.