Ki is a very subtle and complex matter to discuss. If you want to experience what really ki is --- just do Tekubi Furi Undo exercise or shaking exercise. After doing the said exercise you'll notice that there is a current flowing through your arms down to your finger tips --- that is KI.
When we talk about ki development one must be familiar with the so called chakra or energy center. Chakra is a Hindu word meaning 'nerve center' or 'wheel'. These chakras or energy center controls the vital organs of our body. First we simply define ki as energy (whew!.
let's compromise for a while of how we should define ki). I guess everybody understands the word energy.
There are seven major chakras or energy center namely: Crown chakra- controls the brain,pineal gland, browse (ajna)chakra- controls the pituitary glands(this is the so called master chakra), throat chakra- controls the thyroid gland, heart chakra- of course controls the heart, solar plexus chakra- the stomach, the liver, pancreas and the intestines , sex chakra- of course the reproductive organs & this is where our center(one point) is located and the root chakra- at the base of the spine.
The spine is the central channel that runs thru the body, along this channel are seven energy centers or the so called chakras.
If we are talking of KI development, our chakra or energy centers must be aligned first in order for the energy to flow smoothly through this chakra. And we should desist from focusing on our center or one point because it's a very dangerous practice and would even result to death. Being a practitioner of yoga I learned that the higher chakra should be developed first rather than the lower chakra. Because the entry of energy or universal ki is from the top of the head or the crown chakra and it will flows down to the other chakra up to the end of the spine.
The reason behind this is the so called 'Kundalini' located the base of the spine which means "coiled serpent". It is like a power cable, causing it to rise up through the chakras is said to release great powers when it reaches the crown chakra. Our center or one point is parallel to this chakra, when we focus or keep one point we also activates the root chakra. And we are advised not to activate this chakra without the guidance of someone highly trained in the art of kundalini.
The higher energy should be transmuted down to the lower energy center before we trigger the lower energy to rise up. Because the lower energy is coarse in nature and the higher energy are very subtle and refined energy. When the energy flows from one center to another it changes form and some sort of bio-chemical reaction is happening which affects our internal organ being control by these energy centers.
that you do understand my point from esoteric view. I am also an Aikidoka who's been doing some research on Ki Development...nice to butt in