The way people most talk about ki these days tends toward the occultish, but I will say that I have never done anything even remotely involving the occult. Much of what Ueshiba Sensei talked about, on the other hand, did sound like the occult.
In any case, I began studying aikido because I saw that Ueshiba Sensei had truly mastered the art of relaxing. It was because he was relaxed, in fact, that he could generate so much power. I became his student with the intention of learning that from him. To be honest, I never really listened to most of the other things he said.
Stories about Ueshiba Sensei moving instantaneously or pulling pine trees from the ground and swinging them around are all just tall tales. I’ve always urged aikido people to avoid writing things like that. Unfortunately, many people don’t seem to listen. Instead, they just decrease the size of the tree in the story from some massive thing to one only about ten centimeters in diameter. In reality, it’s pretty difficult to pull even a single burdock root out of the ground, so how in the world is someone going to extract a ten centimeter pine tree, especially while standing on its root system? Such things are nothing but exaggerations of the kind often used in old-fashioned storytelling.
The stories have gotten rather incredible since Ueshiba Sensei passed away, and now people are having him moving instantaneously or reappearing suddenly from a kilometer away and other nonsense. I was with Ueshiba Sensei for a long time and can tell you that he possessed no supernatural powers.~ Koichi Tohei from, http://members.aikidojournal.com/public/interview-with-koichi-tohei-1/
From, Interview with Koichi Tohei by Stan Pranin.