Having read a few manga/watched some anime, I have seen that many characters can use attacks where they gather their "ki" or, according to wikipedia, "Life force", and release it in a fireball like manner. The most widely known examples of these are the "Hadouken", and the "Kamehameha". Where does the idea for this kind of attack come from? Did one person think of it and everyone copy them, or is there like a old teaching or story about this?
Thanks in advance :)