As others have already written very complete reviews, I just had a few miscellaneous comments, mostly on how to understand Musashi's seemingly paradoxical ideas about technique.
This has become a legendary book. Written by the famous swordsman, sometimes referred to in the west as "The Lone Ranger of Japan," Musashi claimed to have been in over 60 sword battles, triumphing each time, so it's no wonder Musashi's name has become legendary in both Japan and the west.
The book sets out Musashi's philosophy and correct Way of the Sword. But the principles Musashi espouses are bound to sound perplexing to many people. Musashi says that the best stance is no stance, that too much strength is bad (your sword may shatter when clashing swords), and that even too much speed is bad (it may upset your balance), and that none of these are the true Way of the Sword. The best technique is, in fact, no technique.
This sort of philosophy is bound to be more than a little confusing, so I'll see if I can clarify it a little. I'm not sure I understand Musashi either, although I've studied martial arts for many years and have read my share of eastern philosophy, but I'll give you my ideas on how I relate to them just in case you find them useful.
Basically what Musashi is saying is that once you've learned a technique and committed it to memory and especially "muscle memory," it becomes fixed and is no longer adaptive. Your body becomes channalized into this form or technique, which then becomes limiting, preventing you from achieving true mastery, which is the ability to adapt and flow with any of the infinite number of situations you may encounter. Fixity is therefore dysfunctional and is not the true Way of the Sword. This might be what Musashi means when he speaks of the Way of Emptiness being his way and the true Way of the Sword. In other words, his technique is no technique because it is empty of all fixed, unchangeable, and unadaptive aspects.
There is an analogous principle in Zen. In Zen, the highest level of technique is called "the technique that can't be seen." This doesn't mean that the technique is so fast it's invisible. It's that the technique is so advanced and subtle that its principles aren't obvious and easily seen. Musashi's ideas seem to reflect this Zen Buddhist principle also.
Interestingly enough, this idea has some support from western research into learning and the brain. In learning theory, there is the idea of "stereotyping," (which has nothing to do with social or racial stereotypes), where motor movements that have been learned become fixed into a certain sequence or pattern, but which is not necessarily the most efficient or effective. My learning theory instructor used the example of shaving strokes. He realized after some years that he always did his shaving strokes in the same way, after having learned how to do them, but that they weren't necessarily the best way to shave, anymore. Now that he'd been shaving for years, he "re-engineered" his shaving strokes so that they were more efficient.
This may apply to the martial arts too. After we've learned a certain movement and achieved a certain level of skill with it, we may become complacent and never go back and question the movement again. All because we believe we've achieved a level of "skill." I notice Paul Vunak, an important martial artist in Bruce Lee's Jeet Kune Do and the Filipino martial arts, also emphasizes the learning of principles rather than "technique," and specifically mentions this in his seminars. The idea is that once one has learned the principle behind the technique, one can do an infinite number of those techniques, depending on the situation.
Another interesting physiological principle that is almost as paradoxical as Musashi's ideas has been found by western science. There is a phenomenon in neuromuscular physiology known as reciprocal inhibition of flexor-extensor pairs. This means that during muscle activity the opposing muscle tension is inhibited to reduce effort on the flexing muscle. So if you're trying to do a straight punch, the tricep tenses and the bicep relaxes, thus reducing resistance. The paradoxical aspect arises from the fact that by performing a small jerk backwards in the opposite direction to the punch the outward extensor motion can be speeded up. In kinesiology they refer to this as a "pliometric jerk," and is how basketball players jump higher. But it also has equal application to the martial arts, and I've had good results using this to get more speed and snap in my own techniques and for my students.
Anyway, I just thought I'd offer a few suggestions from my own experience on Musashi's book, although I can't say I fully understand it either. But I hope you find them helpful in some small way in your own understanding and training.
