The following was published on Budo Free Talk on June 2002 (issue #26). It's author is Yoshimine Yasuo, a student of Sagawa Sensei.
There aren't many words which are misunderstood to the extent of the world Aiki. It is quite unfortunate that many dubious martial artist use this term purely for their promotional purpose. As of current state, as far as magazine or books are concered, thre are very few which provide correct information about aiki. If there are ten articles about aiki, probably at least eight of them are incorrect.
The reason why the matter has fallen to such sorry state is because aiki is very difficult to master. So only external forms have been transmitted and it is very rare to encounter genuine aiki techniques. Accordingly, even among people who call themselves Shinan (instructor), unfortunately, only few know it. When someone asks "what is aiki?", often, answers are like "This is beyond the description by words" or even "It's transcendent ability". (You may not believe me but true). Hopefully, I think more open and modern/enlightened attitude will slowly change this and make aiki easier to learn.
Then, what is aiki? I will write technical or methodological detail in my book so pardon me if I'm brief. But anyway, stuff like magazine tend to describe aiki as something mysterious but in reality, aiki is very scientific. To cut the long story short, if you seek the origin of the word aiki, answer will reveal itself.
I wrote this few time in the magazine "Hiden" but aiki is originally kenjutu (Japanese sword arts) term and it describe a state where you and your opponentís seichu (central) line is face to face. (This word is used even in modern kendo as in original meaning). Easiest way to see it is to just pick up swords with your partner, hold it in the middle until the tip of the sword face each other. Obviously, this situation is stalemate. So you have to diver your opponent's tip of the sword. To do this is called "Divert Aiki". It's not even incorrect to state that entire koryu kenjutu techniques are based on methodology of diverting aiki. For example, in case of Shinkage ryu (shin=true kage=shadow ryu=style), they often use technique to enter diagonally to divert aiki. In case of Onoha Ittoryu (Ono branch of one blade style.), it's characteristic is in how to divert tip of the sword by central breakthrough. Aiki of Daitoryu is application of this principle of central breakthrough of Onoha Ittoryu into taijutu. That is, you deliberately force the state of aiki as in sword fight then proceed to break this state through penetrating into centreline of your opponent. Accordingly, the basic stance use the same one as Onoha Ittoryu. And in aiki, attack target are neck and hip (and occasionally chest) and this is, in fact, same as the thrust targets of Onoha Ittoryu.
Therefore, there are broader definition and narrower definition of the term aiki. The broader definition of aiki is the entire methodology of crushing opponent's attack stance through central penetration. This includes atemi (strike) into upper part of the body. Narrower aiki means techniques of neutralising attack from the contact, exemplified in technique, aiki age (aiki lift).
Now, as of aiki age, presently, even this technique are often misunderstood. Many people confuse this with Kokyuho in aikido. They looks alike but their purpose is completely different. That is Kokyuhou or Tenchinage in akido originally meant atemi into jaw with palm. In Daitoryu, there are no concept to push someone down with charge like in sumo. The correct concept is to uplift your opponent or smash opponent directly below and the techniques which exemplify this fundamental principle are aiki age (aiki lift) and aiki sage (aiki takedown). These two use entire body and are not mere hand techniques. Hence by looking at even one photo, one could tell whether someone has managed to do it or not. Extremely bad example is when one push someone down just by using body weight . If one do aiki age from kneeling position, if someone standing losing balance on top of you even if your back is straight and your haven't broken your keeling, then it is the real deal. And if you have opportunity to experience aiki age, pay close attention to the feeling when you grab this person's arm. With someone who can really do this, there are rarely any sensation of grip because there is no collision of power. Accordingly, anyone who push back with force are out of question. And the biggest difference between correct aiki age and the incorrect one are whether one can make the movement smaller and smaller through training. If one try to push back with force or using body weight, one will never be able to do it. That is, true purpose of aiki is to utilise aiki in every taijutu technique by making it smaller and shaper through polishing your technique. That is why I mentioned in other place that if you got wrong teacher, you never make it.
As of side note, it is often said that the secret of aiki age is to "Open palms as in Asagao (morning face, common Japanese flower)" but this is often transmitted incorrectly. "Open palms as in Asagao" in fact point to the entire arm movement in aiki age and not pointing to how one open palm. The reason this theory has spread is probably due either to do with teacher intentionally hid it or someone who hasn't learned it properly spread it. Once you get used to aikiage, you can do it with your hands closed and the reason one have to open palm is only because it is easier to learn. An important point when you open palm is not to put too much force into your finger. This is bit difficult to get unless demonstrated in practice but in beginner's level, you open your palm like when you do paper in stone/paper/scissors. When expert do Aikiage, especially little fingers are very relaxed. And often this technique are split between Aiki of Kote, when someone grab your writs, and Aiki of Mune (chest) or Aiki of Karada (Body), when someone grab your collar or other such places but these two are the same. This is also easier to understand in demonstration but if you know the gist of it, the latter one is much easier one to do it.
Daturiki (Relaxlation) is another equally misunderstood word like aiki, and this world is also uttered in sort of aspiration as in the word aiki so I mention about it here just in case. Daturiki doesn't mean you don't use muscle. Even in aiki, one is of course using muscle. "To relax" simply means "use only necessarily muscle". The phrase "To issue ki" is same with this principle.
To add further, when he was alive, Sagawa Sohan swung steel training staff every days and someone said "That is just muscle work". This is like making speech with your pants down without understanding the fact that aiki as well as koryu kenjutu use entire body movement. In fact, it is natural to arrive at this kind of training if one think about what is needed in Daitoryu. (However, unless one learned proper way to swing sword, one could damage oneís body so I wonít recommend it.)
As stated, aiki is in practice, very scientific. It is true it is based on rather sophisticated principle but it has nothing to do with mysterious transcendantalism. Therefore, to describe aiki mesteriously or even religiously is self evident sign that one hasn't got proper transmission. It is like someone wondering in amazement at magician's work because he doesn't know that magic is a trick. For magician, trick is easy to perform. And the fact that aiki is scientific mean that everyone, as long as they practice seriously can master it. To add further, in some part of Daitoryu, it is said that one can master aiki even if you can't lift anything heavier than chopsticks as long as you receive oral transmission but that is nonsense. This is because the effect of aiki differs according to individuals. Once you got the gist of movement, then you have to reduce the margin of error by applying aiki many many times to various different persons. That is to aim perfection through repetition of movements based on logic. This is the same in any martial arts.
That is it. This time it was rather metaphysical but as I said, I clarify more practical description of technique or theory in detail in my book. So pardon me for that. The next topic will be "utilisation and paradox in form".