By Soke Masaaki Hatsumi
Jutsu means technique, but it also means heart. Jutsu must come from the heart. Therefore, your heart must be straight and honest. If your heart is not clear and straight, your jutsu will be lacking and you will not improve in the martial arts. Lust for victory will not give you the victory. You must receive the victory from your opponent. He has no choice but to give it to you because he will sense your heart as better or truer.
Nature is your friend, it will help you to win. Your enemy will have unnatural movement therefore you will be able to know what he is going to do before he does it. If you want to make only your mind/spirit strong practice religion, not martial arts. Martial arts can kill. On the other hand if you only are interested in making your body strong enough to kill or win honors, lift weights, eat vegetables, and walk to become strong. Don’t bother with martial arts.
I refer to mastery as a feeling in the individual.
The certificate, even 10th degree, is no proof. One must be honest and think on this very deeply. This is the proof, this ability always allows the Budoka to win, his technique always works. Ninpo protects all of you, your body and spirit.
If your spirit is not straight, you can easily get yourself killed.