Takuan Soho, as legend would have it, was friend and teacher to famed Miyamoto Musashi, arguably the greatest swordsman in the history of Japan. As a Zen monk, poet, painter, calligrapher, etc, he lived during a particularly violent period of Japanese history. He therefore confronted war and violence, instructing both shogun and emperor and befriending the likes of Yagyu Munenori, head of the Yagyu Shinkage Ryu school of swordsmanship. Zen and martial arts training maintain a long history of inter-relationships in Japan. Zen practitioners also needed to interact with other religions/philosophies, and did so by supporting each individual in pursuing the belief system of their own choice.

That said, the interaction of Zen monks with famed martial artists during their growth and development can be quite instructive regarding the underling principles of martial arts training. A critical aspect shared by both traditions, Zen and martial arts, is learning to face one's mortality. Takuan, himself, faced death unflinchingly. He requested no funeral ceremonies be done, that everyone simply go about their business for the day, and at the moment of death penned the Japanese character for dream and departed.

In his essay "The mysterious Record of Immovable Wisdom," written to Yagyu Munenori, he addresses certain very basic principles of all martial arts training. I've selected several quotations from the first two sections below:

"Abiding place means the place where the mind stops...

Abiding signifies stopping, and stopping means the mind is being detained by some matter, which may be any matter at all.

To speak in terms of your own martial art, when you first notice the sword that is moving to strike you, if you think of meeting that sword just as it is, your mind will stop at the sword in just that position, your own movements will be undone, and you will be cut down by your opponent. This is what stopping means.

Although you see the sword that moves to strike you, if your mind is not detained by it and you meet the rhythm of the advancing sword; if you do not think of striking your opponent and no thoughts or judgments remain; if the instant you see the swinging sword your mind is not the least bit detained and you move straight in and wrench the sword away from him; the sword that was going to cut you down will become your own, and, contrarily, will be the sword that cuts down your opponent.

...This is what you, in your style, call 'No-Sword.'

If you place yourself before your opponent, your mind will be taken by him. You should not place your mind within yourself. Bracing the mind in the body is something done only at the inception of training, when one is a beginner.

The mind can be taken by the sword. If you put your mind in the rhythm of the contest, your mind can be taken by that as well. If you place your mind in your own sword, your mind can be taken by your own sword. Your mind stopping at any of these places, you become an empty shell...

Glancing at something and not stopping is called immovable. This is because when the mind stops at something, as the breast is filled with various judgments, there are various movements within it. When its movements cease, the stopping mind moves, but does not move at all.

If ten men, each with a sword, come at you with swords slashing, if you parry each sword without stopping the mind at each action, and go from one to the next, you will not be lacking in a proper action for every one of the ten.

But if the mind stops before one of these men, though you parry his striking sword, when the next man comes, the right action will have slipped away...

When facing a single tree, if you look at a single one of its red leaves, you will not see all of the others. When the eye is not set on any one leaf, and you face a tree with nothing at all in mind, any number of leaves are visible to the eye without limit. But if a single leaf holds the eye, it will be as if the remaining leaves were not there...

This religion, that religion, there are various kinds but at their deepest points they are all settled in one conclusion.

At any rate, when one practices discipline and moves from the beginner's territory to immovable wisdom, he makes a return and falls back to the level of beginning, the abiding place.

There is a reason for this.

Again, we speak with reference to your own martial art. As the beginner knows nothing about either his body posture or the positioning of his sword, neither does his mind stop anywhere within him. If a man strikes at him with the sword, he simply meets the attack without anything in mind.

As he studies various things and is taught the diverse ways of how to take a stance, the manner of grasping his sword and where to put his mind, his mind stops in many places. Now if he wants to strike an opponent, he is extraordinarily discomforted. Later, as the days pass and time piles up, in accordance with his practice, neither the postures of his body nor the ways of grasping the sword are weighed in his mind. His mind simply becomes as it was in the beginning when he knew nothing and had yet to be taught anything at all.

In this sense one sees the beginning being the same as the end, as when one counts from one to ten, the first and last numbers become adjacent...

...of the beginning, the abiding place and the immovable wisdom that comes later become one. The function of the intellect disappears, and one ends in a state of No-Mind-No-Thought. If one reaches the deepest point, arms, legs and body remember what to do, but the mind does not enter into this at all...

There is such a thing as training in principle, and such a thing as training in technique.

Principle is as I have already explained above: when you arrive, nothing is noticed. It is simply as though you had discarded all concentration...

If you do not train in technique, but only fill your breast with principle, your body and your hands will not function. Training in technique, if put into terms of your own martial art, is in the training that if practiced over and over again makes the five body postures one.

Even though you know principle, you must make yourself perfectly free in the use of technique. And even though you may wield the sword that you carry with you well, if you are unclear on the deepest aspects of principle, you will likely fall short of proficiency.

Technique and principle are just like the two wheels of a cart."

I suspect most of the words written above, on some level are familiar to those who practice in the dojo. For example, on technique versus principle, Saito Sensei has often explained that there are two sorts of people in Aikido, those who talk about practice and those who do it. Regarding the unconscious ability of the body to respond naturally to attacks, Sugano Sensei terms this muscle memory. He also describes the way to look at an attacker, "glance as if looking at a mountain in the distance." In other words, don't look at his fists, his hips, or any specific aspects of their body in attempting to calculate how the attack will be launched and/or how you will respond.

However, the central theme his is the abiding mind versus the mind that does not stop. The description of how these aspects change throughout one's practice, from beginner to middle to expert levels, is very important. Consider this point in how you train on a daily basis. How does the stopping mind leave you open to be defeated. We may begin to see this in some small way in daily practice, but it is also important to understand the process on an intellectual level, so we may become more aware of what is happening in practice and consider them in more depth.