|Asura in Kōfuku-ji, Nara. photo by 小川晴暘|
Ask your teacher what it is. Many will give you their pat, standard answer given to all beginners. Others will wander off in a glassy-eyed, meandering philosophical and esoteric treatise. And there are even some who will try to tell you how to stand or step while delivering a punch.
They may not be wrong. But they probably will be missing key ideas. I will not try to correct anyone except to say, please discard what you think you know.
Hatsumi Sensei recently gave us a clue to the secrets of sanshin when he was teaching us about kaname:
全体を捕るということは、要をとる。三身一如のことは言う。Soke suggests here that you take everything together by only taking what is essential in the moment (kaname). This is sanshin unified as one reality. Three as one.
To me this is like the hidden door of Togakure, an opening to understanding sanshin. When you open this door you find your reflection in a mirror. The secret is polishing the mirror (and your heart) with training so that reflection is pure like the clear water of 平常心 Heijōshin.
You may have heard about 三心 sanshin. And that is good. In Budo this is 心技体 shingitai: mind/spirit/heart; technique; body. Or if you want to be more philosophical: 身心識 body; heart; consciousness.
These are important ideas. But Soke used the kanji 三身一如 for sanshin ichinyo. This implies more of a Buddhist cosmology. 三身 is the trikāya or threefold body of the Buddha. This symbolism is complex but I will polish the mirror a bit.
The first is the Dharmakāya, truth body. This reflects your essential nature and character. This begins with a new student who studies hard, rarely missing a class. Staying true to the kihon and forms until a breakthrough of understanding occurs (for some students, around Godan level). Looking for the limits of your nature, you discover your truth to be limitless.
The second is the Sambhogakāya, or reward/retribution body. If you trained well, you may reap the reward of joy in life and training, or blissfully enduring battle. Your reflection will be pure in the mirror. If you did not train well, your frustrations in life, the dojo, or losing and being injured in battle, will surely shatter the reflection.
Third is the Nirmāṇakāya, the manifested body or actual physical form. This transformational form also embodies henka. Take your clothes off to see this one in the mirror. Maybe you don't want this reflection to be too clear!
So how do we use this in class or combat? Soke says 三身一如. Bringing the three together as one at the essential moment (kaname). If you have not been polishing well, this will be impossible.
Another three faced symbol shows us what NOT to do: the 阿修羅 ashura or fighting demon. These are the reflections of students who are obsessed with ego, force and violence. They may be quick to anger, full of pride, envious of others, insincere with their motives, false or fake in their persona, boast full, lazy or worse... bellicose.
The mirror of the heart dims. What this means is that they are unable or unwilling to learn or train Bujinkan as it is taught. If they are teachers, they often trap themselves along with their students.
But if you unify 三身 sanshin in combat, the results are really miraculous. I've witnessed it. I've experienced it myself. Trust me, you want this. Are you ready to study Sanshin?