Visualize your body as a fluid.
Your viscosity is fairly uneven. Some regions flow more freely than others. In general though, the viscosity is high. So sticky, in fact, that there is something like a containment region where no part can flow beyond proximity to other parts.
Nevertheless, you can flow.
Whenever an energy or force enters you, you can move with it. Practice doing so.
"Go with the flow," and "Be like water" are useful starting points, but they are limited. You are an unusual fluid -- you are not only responsive, but also self-motivating and self-directed.
You are not passive. You yourself are a reservoir of energy. You are not only the fluid, and not only the flow, but you are also the cause of flow. You are a source.
Practice this in your body until you understand it deeply. Then do the same with your mind and your emotions. Visualize your thoughts and experiences as fluid.
Now do the same for your partner.
Now do the same for your world.
All things are fluid. Fluidity creates structure.
Structures within fluids result from a combination of the properties of viscosity and inertia. Among those who study fluid dynamics the ratio of these properties is called the Reynold's Number. When the Reynold's Number is in a certain range, laminar flow results. In a different range, turbulence occurs.
Laminar flow is movement in parallel, like sheets moving across one another. Laminar flow is smooth, and mostly in the same direction, even if the velocities are a bit different. Well-behaved traffic patterns might be one rough analog of laminar flow. In aikido, we see it when uke and tori are moving together in the same general direction.
Turbulence is more complex, with eddies and whirls. These structures serve to resolve chaotic patterns into simpler laminar regions (though circular) yet at the same time obstruct other areas of laminar flow.
Turbulence exists across a wide range of complexity. The break point between laminar and turbulent dynamics is often quite beautiful. A high degree of turbulence is more than the mind can grasp.
Aikido lives at the boundary between laminar flow and turbulence.
Returning to the idea of your body as a fluid, we may say that the nodes of lesser freedom are like eddies and whirls. Your joints are a good example, being centers of relative stillness around which movement occurs.
When two or more bodies encounter one another, each complex system joins with the other. Complexity is quantitatively increased, but qualitatively remains largely the same. In other words, two or more moving bodies in a system are conceptually the same as one body with moving parts.
The main consequence of all this, and really the central point, is that such systems have regions where there are more degrees of freedom and regions where movement is tightly bound and comparatively restricted.
Resistance to flow is created by the flow itself. This is unavoidable. What aikido can teach us is how to minimize unnecessary nodes of resistance.
To do this, you absolutely must practice flowing with your partner's energy. Moreover, you must do this in a way that does not allow pressure (resistance) to build up inside your own system. You must be able to flow with your partner in whatever direction they take you, while directing your own flow away from becoming bound up within yourself. This is a very demanding discipline.
Only when you have sufficient proficiency in this should you attempt to significantly alter the structure of your partner's flow. Any effort to do so should be in the same spirit of not increasing pressure within the system. You should not be attempting to bind your partner in any way.
Move where movement is most possible. Do not move against the things which resist movement, beyond what is necessary to encounter them and discover the truth of them. Flow over and around obstacles, and direct flow around your own more rigid structures. Never plant your feet, and under no circumstances should you try to become rooted to a fixed position.
That said, energy seeks a naturally grounded state, and providing sensible pathways for it to do so is good aikido. Observe and facilitate flow from higher energy states to lower ones.
One more thing: this is practice, not combat. This is a practice which should, among other things, improve your skill in combat, but it is not to be mistaken for combat. In actual combat you are free to do whatever is necessary to preserve life. Immersion in the discipline of flow will help, but be prepared to step outside your discipline whenever necessary. After all, that's part of being fluid, isn't it?
Accordingly, you should understand that this method is not aimed at how to execute a flawless ikkyo on a stout and recalcitrant partner. That lesson is valuable on its own merits, but belongs in a different category.
Paradoxically, by going around the ikkyo, the resistance to ikkyo frequently melts away, and ikkyo simply flows into place. However, when this is so, it is incidental. The main goal is the understanding of flow and the structures which both impede flow and yet may resolve it locally.
In this view, ikkyo (for example) may be seen as a vortex. Find its center of stillness and do not move against that. Observe the ways in which the structure is circular, then move along its periphery, the way the main body of water flows past a whirlpool. Where the whirlpool and the main current come together is a laminar boundary. Do your aikido there, and be both keenly aware and heedless of the form of ikkyo.
Turn with the turning. Turn the turning.
Move with the stream, but also with the stream's consciousness of the ocean.
By all means go with the flow, but remember too that you are the flow.
Still Point Aikido Systems
Austin TX, USA