The original translation is very deep and spiritual and may be tough for the general public to understand. I therefore provide a modern approach translation while still maintaining the essence so everyone can enjoy regardless of experience.
Through martial arts strategy the skills of self protection can be used to protect oneself ( Body/mind). However the highest level of defence can be reached through Ninjutsu ( spirit). It is important to establish good ethical background. If do not maintain the correct attitude (spirit) in the martial way you are likely to cause yourself or others injury or death. If we use medicine as an analogy it’s primary function is to aid in healing however if one develop dependencies beyond the prescribed use, it can lead to imbalance causing harm. The same with food… We need food to sustain life. However excessive use through overeating or eating unhealthy will destroy our body. Politicians have the responsibility to serve and protect their citizens. However if a politician is consumed with too much desire and greed or lack of wisdom it will cause imbalance within its constituents and country. The same is true for religion; if a religion is true and sincere, then it can aid people to achieve balanced living and help society prosper. If a master of the martial arts is to truly study Ninjutsu he must learn the secret of Kanjin Kaname and develop the foresight of Shinshin Shingan. Through attaining this wisdom and character one can walk in the path righteousness. For man this is called having faith and follow natural laws.
The use of the five elements of Moku / Ka / Do / Kin / Sui (Wood / Fire / Earth / Metal / Water) gives insight to the dependencies of existence. With nature the seasons come into existence. If any of the seasons contain imbalance then nature will need to find a way to correct itself. When human beings follow a righteous, sincere and correct life then they can be in harmony with nature and the divine. Understanding these Universal Laws one can live with harmony with all living beings.This is having the wisdom of foresight to see things for what they really are.
It is a prerequisite for a Ninja to be righteous and have this understanding. To be able to study Ninjutsu one must be able have this wisdom of foresight and tell the difference between right or wrong. It is said that Ninjutsu originated through Cho Busho and Cho Gyokko. Though these founders many theories came about. It is said they brought with them and transmitted the knowledge of Karate Hicho Jutsu, Koppo Jutsu, Senban Nage Jutsu and other skills. These later formed the foundation of Ninjutsu.
Those who followed their teachings were able to attain this wisdom and foresight through rigorous training and meditation. There is a a reference to a place where famous masters obtained enlightenment. This place still exist to this day. In the past this place was called Tojin Iwa.
One of the many skills they developed was to use their willpower to subdue their opponent. This development took place in the Iga area and through warriors from Fujiwara, Minamoto, and Taira Clans who sought refuge in the mountains of Iga the art naturally evolved to what its known today, The formation of Happo Biken Jutsu was transmitted through generations. It is said that martial art which uses the number 9 and has 9 methods or ways makes for absolute victory.