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Time, Space & Mind: The Three Dimensions of the Reactionary Gap

By Jeff Brooks

To strike your opponent successfully you need to enter through a gap in his defenses. If your opponent’s defenses are sound, you cannot enter and you cannot strike them. There are a variety of ways to enter. You can crush the defenses. You can deceive your opponent into misplacing his defense and so take advantage of an opportunity where he is exposed. You can perceive a weakness in your opponent’s posture or awareness, or both.

In medieval Japanese budo these openings in the opponent’s defenses, these opportunities to strike, were called “suki.”

The idea of suki has been discussed at length in several famous books on Japanese swordsmanship. The classic medieval Japanese text, published in modern times as one of the essays in “The Unfettered Mind,” was actually a letter written by Zen monk Takuan Soho addressed to Yagyu Munenori, sword master to the family of the Shogun, the military dictator of Japan at that time.

Takuan was a very influential person, abbot of one of the chief Zen temples in Japan. He was equivalent in influence to a Pope in medieval Europe. He was a retainer of the military government. He addressed his comments to the senior instructor in the most prestigious military art in the highly militarized world of his time.

His comments were ostensibly a discourse on swordsmanship, but can easily be read as advice in Zen practice, using swordsmanship as a metaphor. In his letter he applies Zen insights and theory to the practice of swordsmanship. Takuan did not practice swordsmanship himself. He may have been motivated by a desire to persuade the leaders of his nation of the practical utility of Zen in the life of the samurai.

Takuan talks about avoiding “suki” by means of the “mind abiding nowhere.” This is an application of the theory underlying the Zen practice of “samadhi” – the cultivation of mental stability and clarity in seated Zen meditation – to the practice of combat with swords.

D.T. Suzuki, one of the leading importers of Zen to the west in the early 20th century, cites Takuan’s letter and analyzes it, in his famous book from the 1950’s “Zen in Japanese Culture.” Suzuki was a scholar, trained in western philosophy, but also in the practice and theory of Japanese Zen.

Both Takuan and Suzuki emphasize the identity of the mind that is completely free to respond unhindered to the demands of the moment with the mind that is immovable – not deflected by either stimulation or impulse.

Both Takuan and Suzuki seem to take for granted that a suki arises as a result of a mental flaw – a gap in attention or alertness. As acute as their observations are, this presumption is one-sided, probably due to the fact that these two commentators were not martial practitioners and had a psychological bias to their analytical approach.

I have seen less-experienced fighters go to the other interpretive extreme. In a sparring match or a confrontation, these individuals look for a physical “gap” in the defenses of the opponent. Waiting for a physical gap to open up, their fleeting opportunity is lost. They lose initiative and fall into a reactive mode in which they respond to their opponent’s initiative and lose any advantage they may have had.

Their analytical prejudice is physical – they neglect other aspects of combative engagement.

Today in martial arts and police combative training we work with the same set of phenomena as medieval Japanese martial artists did. The opportunity to take advantage of a suki or gap in an opponent’s defense, and at the same time avoid a window of vulnerability to open in our own defenses, arises in three dimensions of experience simultaneously: time, space and mind.

The dimension of mind has several aspects. One aspect is alertness. This is a cultivated ability to maintain a clear and stable focus on the matter at hand, without being distracted by parts of reality such as the opponent’s body, elements of the environment or by one’s own thoughts, emotions and impulses. This ability is developed. You have to practice stability and clarity under pressure, just as you have to practice physical technique, to increase your strength, speed, endurance, balance, focus, etc.

Another aspect of the dimension of mind, however, is not trained but inherent. Although it can be modified slightly it cannot be eliminated. So if we are aware of it, and know how to use it, we can take advantage of this flaw in our opponent’s ability to respond to our attack. This aspect of mind is called the “reactionary gap.”

An unanticipated arms length attack is almost impossible to stop. That is why as a police officer you are taught not to permit a subject within your “reactionary gap.” The reactionary gap can be described in space – as a distance of six feet from an empty hand opponent, let’s say, or it can be described in time, 300 to 500 milliseconds for a normal person, to perceive an opponent’s motion, interpret it and respond to it.

A major league baseball player has a reaction time of about 100 to 150 milliseconds, much faster than an average person, but still slow enough for a skilled pitcher to get a well-thrown breaking ball past him.

A famous test of the reactionary gap in armed encounters is called the Tueller Principle. The idea came out of a court case in which an officer shot a knife-wielding subject at what seemed to the jury to be a great distance. Upon testing the by defense, it was shown that a knife-wielding subject could close the distance on an officer with a holstered gun and kill the officer before that officer could draw his gun, from a distance of 21 feet or greater. And that was an average subject and an average officer. Given a subject who is a fast runner, or an officer whose attention is divided or is slower in drawing his firearm, that reactionary gap can open to 30 or 40 feet or more.

The effectiveness of any response to threat stimulus will depend on the sharpness of the attention of the responder, but also upon the mental habit of responding to attacks, and the physical skills that will permit the body to perform accurately, with strength, skill and speed, under pressure.

We will respond, successfully or otherwise, in the dimensions of time, space and mind.

When old books describe becoming “one with the opponent” they are not recommending that you become the same as that person, indistinguishable from him or with the same objectives or methods as him.

The injunction in that poetic phrase is to close the gap between your mind and his mind, between your body and his body. With practice you can intuit how quickly he can respond… you can sense positions in which you can close the distance to him and execute a technique in an unexpected way… you can feel when you can enter his reactionary gap without opening up one of your own.

This does depend on taking the initiative, courageously engaging without doubts and scruples. But it does not mean plunging heedlessly in, needlessly jeopardizing your position, like a kamikaze on a desperation mission.

I worked with a group of new trainees who were asked, on the first day of training, to take one of their instructors to the ground. The instructor was highly skilled. Although they did not have the concept of “finding a gap” it was evident that the trainees could not find a gap in their instructor’s defense. One by one they lunged at the knees or hips of the instructor, with a mixed martial arts type of approach. Each one failed to achieve his objective.

Over the course of the training their skill did increase and they were able to take command of the confrontation, even when faced off with some highly awesome instructors. And one of the things these trainees learned which allowed them to be effective was never to abandon control of the situation, plunging in while neglecting the qualities of the moment, without an objective for each action, without regard to the outcome of the encounter.

The body has to be trained and skillful. The mind has to be stable and strong. The will must be resilient – neither impetuous nor hesitant. That way we can assure that we will perceive and exploit the suki in our opponent’s defenses without opening any gap in our own.

Sun Tzu (the famous Chinese philosopher) does not use the medieval Japanese terminology, nor does he fall prey to either extreme of strategic analysis – too much emphasis on the psychological or too much emphasis on the physical. But he does, throughout his classic book “The Art of War”, address this very issue: how best to recognize and exploit the weak points in your opponent’s defenses, while avoiding exposing your own.

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About The Author:

Jeffrey Brooks, Seventh Degree Black Belt, US Shorin Ryu Karate, has been the director of Northampton Karate Dojo in Northampton, Massachusetts since 1987 and director of Northampton Zendo since 1993. He is a police officer and police instructor, and the author of “Rhinoceros Zen – Zen Martial Arts and the Path to Freedom.” His column Zen Mirror and other articles appear on

New! is pleased to announce its first book: “Rhinoceros Zen –Zen Martial Arts and the Path to Freedom,” by Jeffrey Brooks, a work that portrays the dual paths and interplay between Zen and Karate-do. Fast paced and easy to read, it is full of insight and wisdom. It is a rewarding read for any martial artist.

(Softcover, 300 pages, illustrated)


To find more articles of interest, search on one of these keywords:

Zen and the martial arts, suki, karte fighting, kumite, The Unfettered Mind,Takuan Soho,Yagyu Munenori

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