The Unbendable Arm
by Gordon Anderson
Another person cannot bend the arm of a person who has trained himself to stay relaxed and lets his spirit flow through his arm
"Strength of the spirit is real strength. If you believe that your spirit strength is flowing out, it is, though you cannot see it with the eyes of your body. If your spiritual strength is coursing through your arm, trying to bend it will be like tying to bend a fire hose through which water is racing."
"Aikido In Daily Life"