The term O Sensei indicates a truly great teacher. This is someone who not only instructs, but inspires. It is a term that can apply to a teacher on any subject.
The founder of Aikido, Morihei Ueshiba has often been refered to as O Sensei. But is he really?
Some aikidoists say that there will never be someone as good in Aikido as its founder. If this is true, then Morihei Ueshiba should not be called O Sensei because he was never able to train someone up to his level.
Personally, I think there are a group of aikidoists and I certainly am not in this group, who are as good or better in Aikido than its founder. They are not members of any one style or organization, yet their Aikido is as good or better than the founder's. If not on a general level, then in specific arts, especially areas that they have helped develop.
O Sensei was a human being who accomplished a great deal. He was able to do that by understanding his own humanity.
Some people have a self-effacing worship of the founder. Some writers have even place him in a position of a divine being. They emphasize the mystical nature and enlightenment of the founder. This seems to be a path of self-deception. However taking this viewpoint, Morihei Ueshiba cannot be called O Sensei because in their estimation, he was never able to train someone up to his level.
Morihei Ueshiba was a person. A person who had powers that we all have.
[size="1"]With apology to Ellis Amdur