“The secret of aiki is to overpower the opponent mentally at a glance and to win without fighting.“1 — definition of “aiki” by Sokaku Takeda, founder of modern Daitoryu Aiki Jujutsu.

“The most profound and mysterious art in the world is the art of aiki. This is the secret principle of all the martial arts in Japan. One who masters it can be an unparalleled martial genius.” 1
– from the earliest book to mention “aiki”. (1899, Budo Hiketsu-Aiki no Jutsu).

“Aiki is an impassive state of mind without a blind side, slackness, evil intention, or fear. There is no difference between aiki and ki-ai; however, if compared, when expressed dynamically aiki is called kiai, and when expressed statically, it is aiki.” 1
– from the 1913 textbook of jujutsu. (Jujutsu Kyoju-sho Ryu no Maki).

“Aiki is to pull when you are pushed, and to push when you are pulled. It is the spirit of slowness and speed, of harmonizing your movement with your opponent’s ki. Its opposite, kiai, is to push to the limit, while aiki never resists.

The term aiki has been used since ancient times and is not unique to Daito-ryu. The ki in aiki is go no sen, meaning to respond to an attack.

… Daito-ryu is all go no sen — you first evade your opponent’s attack and then strike or control him. Likewise, Itto-ryu is primarily go no sen. You attack because an opponent attacks you. This implies not cutting your opponent. This is called katsujinken (live-giving sword). Its opposite is called setsuninken (death-dealing sword).“ 2
– Tokimune Takeda (son of Sokaku Takeda) commenting on “aiki”.

“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, there are very few which provide correct information about aiki.“ 3
– Yoshimine Yasuo commenting on “aiki”.

“Aiki is a means of achieving harmony with another person so that you can make them do what you want.” 4
– Morihei Ueshiba.

1. Draeger, Donn F. Modern Bujutsu & Budo: Martial arts And Ways Of Japan, Vol III. Weatherhill, Tokyo 1974, 1996.
2. Pranin, Stanley. Daito-ryu Aikijujutsu; Conversations with Daito-ryu Masters. Interview with Tokimune Takeda from 1985-87. Aiki News Tokyo 1996.
3. Yoshimine Yasuo in Budo Free Talk (issue #26, June 2002).
4. From Admiral Takeshita’s diary of his training sessions with Morihei Ueshiba Sensei. Among Ueshiba Sensei’s statements quoted in this diary.