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… - Miyamoto Musashi

It is difficult to know yourself if you do not know others.

Some of the world's strategists are concerned only with sword fencing, and limit their training to flourishing the long sword and carriage of the body. But is dexterity alone sufficient to win? This is not the essence of the Way. I have recorded the unsatisfactory points of other schools one by one in this book.

I have climbed mountain Iwato of Higo in Kyushu to pay homage to heaven, pray to Kwannon, and kneel before Buddha. I am a warrior of Harima province, Shinmen Musashi No Kami Fujiwara No Genshin, age sixty years. From youth my heart has been inclined toward the Way of strategy. My first duel was when I was thirteen, I struck down a strategist of the Shinto school, one Arima Kihei. When I was sixteen I struck down an able strategist Tadashima Akiyama. When I was twenty-one I went up to the capital and met all manner of strategists, never once failing to win in many contests.

What I call the void is where nothing exists. It is about things outside man's knowledge. Of course the void does not exist. By knowing what exist, you can know that which does not exist. That is the void.