Imagine a house. Generally speaking, a house has an exterior
structure. In the normal sense, there is air all around the house,
and there is air inside the house. Air is air - there is no
difference between the air outside and the air inside. (Unless
something has affected the immediate state of the air inside or out,
but that's a different part of the story.)
The only difference in perception between the inner air and the outer
air is caused by the walls and roof of the house being there; the
structure as we see it, and experience and live within it. This is
what creates two localities and causes a perception of duality.
However, it is very easy to see, in this kind of example, that in
fact there is no real difference between the air inside and the air
outside. If we understand that the structure doesn't truly divide the
two spaces, we can see that the air is "one entity," one vast "body"
that is moving, flowing, circulating.
So it is with Ki.
One way to look at Ki is as the fundamental manifested energy, flow,
and life force of the universe. There is Ki all around us, flowing
everywhere, like air. There is Ki inside us; our sustaining energy.
The body, in this case, as we perceive it, is like a house. It
perceptually separates us from knowing the unity of our inner Ki with
the outer Ki. This perception keeps us in a state of duality. To
transcend this, all we need do is step outside of this perception of
"ourselves" as being the dividing entity between inner and outer Ki.
When we do this, we can know that the Ki around us and the Ki within
us is the same, and that it is unified just like the air inside and
around a house.
By being kinesthetically aware of the feeling of flow within us,
emanating outward from the Hara, or center, and learning to trust
that more than the conventional muscular processes that we usually
rely on to support our sense of physical reality, we can release our
total reliance on the body and open up to the experience of this vast
resource that is flowing everywhere. We can draw on the Ki if we let
go of our immediate attachment to our physical and personal
references as the sole source and focus of our identity, power, and
movement, and let ourselves experience and be aware of the fullness
of this "universal" Ki flow, within and without. This is the "key" to
using Ki in Aikido, or in life.