The purpose of ki-aikido is not self-defence; that is a mere by product. It is far more important to learn to control the mind and body. It is too la… - Koichi Tohei

If you throw a stone into a lake, it makes waves on the surface. Eventually the waves disappear, but just because you can longer see them does not mean that they are really gone. They have just become too small for us to see them. In the same way, we calm our mind by half, half, half... and the waves of the mind become infinitely calm. They never actually stop.

Ki is a very complex word... and even more difficult to translate to westerners.

Just as the number one never can be reduced to zero, once we act or speak, our action or speech is never completely erased. An old oriental saying tells us, "sow good, and the harvest will be good. Sow evil and reap evil". We must understand that everything we do comes back to ourselves. Therefore before wishing for our own happiness and welfare and that of our children, we must do good in secret. To do good in secret means to act without seeking attention and praise, to act without any hope of reward. This is called "intoku". Among the various ways of performing intoku, to walk the way of the universe and to lead others along this way is best.