To be at one with; you need to know how to be centered and stable first. So first let's look at the physical aspect of this principle.
Everything has a center, Its’ point of balance, its’ center of gravity, its’ center of stability.
Energy wise what is center?
Well if you spin a ball or even if you spin a table, you will find it turns around its own center and hence follows a principle of physics. The energy being produced by this action is energy motion. There is a force being created here called centrifugal force, where energy is going out away from the center. There is also another force being created here called centripetal force, the same as gravity where energy travels towards the center - two forces at play.
In Aikido physically, you can see the use of the principle for the person being attacked or held, turns around their own center and thus the attacker’s energy or force coming in, is now expelled outwards. Have you ever held a toddler and spun around so that the toddler flies out around you? It's the same principle at work. So you will find your own center around which you are turning is about an inch below your navel.
Let's look at this spiritually. You have a space, a personal space around you that is your own spiritual space. It's usually at about arms length around you, in other words if you were to extend your arms out horizontally you would be showing yourself the diameter of your space. So you have a natural spherical space around you, this spiritual space has a center, which is about one inch below the navel. Let's say it is outside of the body to remind us it's not physical. The rules of energy that apply here are more profound!
From this center you give out energy as in centrifugal force and you also receive energy into this center as in centripetal force but as it is your own center you do it. So to put it simply; CENTER IS THE POINT THAT TAKES IN AND GIVES OUT ENERGY OR KI. Center is also the point around which everything revolves.
So what we have here is a center from which energy goes out and energy goes in and energy also goes around.
All engineers know these principles and hence construct things accordingly, so we are talking here about three naturally preferred paths of energy.
When you throw a pebble into a pond, you will see ripples going out from center and ripples going back into center and you will see them as circles. Thus you can see the natural way of energy.
When an opponent in Aikido is holding you he/she is sending energy into your body. If you let that energy go to your center instead of trying to fight it, then you are immediately going into harmony with his/her energy. If you now turn and extend energy outwards from center his/her energy will then follow the law of centrifugal force and he/she will follow it. It looks like you are merely deflecting the opponent but this is not the case, for you are taking in and giving out thus aligning yourself with the truth of energy.
Now let me take you back to your space. The circumference of your space is of course circular, and this circle is just like the orbit around a planet. Hence, if you spin and let go of your opponent he/she will fly off out of orbit - but if you keep connected to the opponent he/she will orbit around you as you turn. Just like if you swing an object around your head on a piece of string.
Trees grow upwards and therefore have energy going away from the center in a straight line and thus follow straight lines of energy.
When you have a rush of energy drawn to a center, or away from a center you get spirals and therefore put simply, you have the behavior and pathways of energy, all utilized in Aikido.
To get some reality on this let's start with your space.
Sit quietly and feel your own personal space.
You will feel it, and you will feel your body relax.
You will feel your space is REAL.
Now, when you are going about your business in life think about the times when you were aware of someone entering your space, when someone crossed the borderline of your space, your circle. You see you can feel it. Also you can do things with your space. Sit comfortably and expand your space to the walls and the ceiling and you will then experience having the space of the room as your space.
In Aikido you always practice keeping your center and keeping your space.
To get some reality on energy going in and out of center,
Sit quietly and get the concept and feeling of welcoming.
You will feel energy going into your center.
Now get the concept and feeling of offering. You will experience energy going out from center.
These are not things you can't do and are not things you have to wait twenty years in martial arts to become aware of. They are real and natural, and you do it to a degree already.
Aikido is a discipline of being aware of and keeping these principles in life and living. When you get angry you have gone against and hence lost your center, your space and yourself, and this happens when you go into any negative emotion or condition. Instead of BEING you have BECOME. It's not because of what someone else did or said or any other reason you may give, it's because you didn't keep center and keep your space.
Coming back to Aikido and the use of center, by keeping center you can accept and receive the force aimed against you and let it go to your center and consequently not have to revert to force and resistance and fight, you can relax and stay calm. Also it is the place from which you can give back energy at the same time and thus stay stable. In Aikido you operate from center as you should in life.
In summary center is the point in Aikido from where you receive and lead and therefore create harmonious motion. You are the center of your life which you create from center, so how then can you blame anyone for anything?
ACCEPT WITH HUMILITY, PERCEIVE WITH COMPASSION AND LET ALL GO TO CENTER.