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The Geometry of the Spear

I composed this article several years ago, it is essentially rough and unfinished - the diagrams were roughly sketched on paper.  Besides taking out some small sections that had what are considered 'secrets' I have elected to keep the article in its original form, down to the lazy hand sketches.  As is so often the case you start working on something and it then goes on to become part of a larger work - so it will never be revisited in its singular form.

The Geometry of the Spear

This discussion comes about from trying to understand the Kenjutsu of a certain Koryu. This system has a focus on structure but does not emphasise Hanmi as I was taught it. I have removed some parts of this section.

The template and focus on structure I found quite useful, however for me the question in my mind was ‘How does this work without Hanmi?’ which of course poses a question for those of us who see Hanmi as important as Shizentai – what does it give us?

I like to use the spear here as the spear can be thought of as having infinite penetration along its direction of use due to it being the longest of held weapons (here infinite is simply always sufficient not indeed infinite), especially when compared to the sword.  It is therefore inadequate to defeat the spear using a position or structure that is not safe from is reach - it will not run out of penetration.

How the Koryu Works

In a nutshell I came to realise the template works as the opponent utilises the same geometry as the proponent, being an equilateral triangle. This has certain implications. I will start with looking at the singular.

In most people the length of the arm from the elbow down is roughly the same as the width of the body. When standing square and bringing the hands to the middle (as when holding a sword) the structure that is formed is essentially an equilateral triangle.

The centre of the body faces the apex. The base of the triangle is the body, and it is therefore the base that we are trying to strike with the spear or protect. These natural triangles are the ones in which power can be applied and that the structure of which is strong – with a square base the strong structure is always the equilateral triangle. This means with a shorter weapon the strong structure can be achieved with the weapon in any position within the funnel (shaded area below) created by the lines of the sides of the triangle.

When holding a long weapon and remaining square, the fact that the base and one side of the triangle are the same means the equilateral triangle is maintained and the natural position of the long weapon is the remaining side of the triangle with the hand at the hip.

With the long weapon contacting the hip the strong line is limited to the line of the side of the weapon.

When two equilateral structures are pitted against each other the control of the centre by being first to the power structure means the weapon of the opponent is pushed to an angle of at least the side of the triangle and therefore the axis of the weapon will be outside the body edge.

It is particularly easy for the sword to push the long weapon to this axis as the strong structure of the long weapon is not encountered until this line.

In a nutshell this is how the Koryu is working - utilising the structure to push the other weapon to the body-line. The movement of the equilateral structure to combat the early control of the centre is limited to moving the whole structure to another position or moving the shorter weapon within the funnel.

The Hanmi Structure

A stable triangle structure can still be maintained with different configurations as long as certain rules are met. The body is always going to be the base of the triangle, and one of the arms (the lead hand) is going to be one of the sides - these lengths are still the same due to simple anatomy.

The angle relating to the body and the forearms can change to a degree, the arrangement of which will be limited by the angle of the arms keeping the apex of the triangle towards the front and the possible physical extension of the rear arm.

As the angle between the lead hand and the body increases the centreline needs to be orientated towards the apex. This means the body is essentially closing towards the apex and the angle is increased. The open stance is ideally at the equilateral but can be maintained to a degree (with a loss of power) until the lead hand reaches a right angle, once an obtuse angle is reached the body must be Hanmi.

The Static Hanmi

When we follow the axis of the spear in Hanmi we see that the angle of penetration is much more shallow than that of Shizentai (the equilateral), bringing the body of the opponent into contact whilst keeping the body edges of the proponent inside the body edges of the opponent. In this sense engaging the open stance with the closed stance gives a much higher percentage than the previously matched open stances.

Hanmi Meets Hanmi

It may be tempting at this stage to conclude that Hanmi trumps open however let us first examine Hanmi meets Hanmi.

The sword and the spear will typically produce a mirror image as the lead hands tend to be different. In this example the effectiveness of the closed stance is much less certain as one of the body edge lines is no longer cleared simply through the structure.

Similarly, we find in matching Hanmi stances in spear against spear there is no gain or loss through the structure itself.

We must therefore come to the conclusion that it is not the fact that one structure is open and one is not, but that on is less open than the other that makes the difference.

How The Open Stance Attacks The Closed

The open stance, here sword, can negate the use of the closed stance by moving the entire structure to the point where the power line of the closed structure is no longer in line with the base of the triangle - this achieves the same outcome as the original intention.

Tightening Hanmi

The closed stance can overcome the closed stance, or the repositioned open stance, by further closing the body. This achieves the original intention of the closed stance targeting the base but moving within the body edges.

It is, for this reason, a completely closed (side on) stance is not the ultimate stance. If it were simply that the more closed the body the better the stance that would be the case, however there is additional value in the closed stance having the ability to tighten further.

The Yin and Yang of the Spear

There are then as usual two components which when combined will form the ideal use of the spear:
- The movement of the structure.
- The tightening of the structure.

It is important to remember that this work was left at this stage and that it does not constitute the whole of the story.  When we look at the two configurations statically the one that is closed may have a superior (in this context) angle however the one that is open has more ability to tighten the angle - and one should also consider the amount of angle contained in 'the funnel' when considering the potential for repositioning.  The intention is to get a jumping on point for some of this geometry.

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