Kū

The "Void" (Kū) is the final book in Miyamoto Musashi's "The Book of Five Rings," a text on kenjitsu and the martial way, written in the 17th century. This chapter is both the culmination of the prior teachings and an exploration into the most profound philosophical aspects of Musashi's strategy. Unlike the preceding books—Earth, Water, Fire, and Wind, which focus more on the physical and tactical elements of combat—the Void book delves into the spiritual and philosophical underpinnings of Musashi's way of the warrior, or "Way of Strategy."