In martial arts the statement, "the key to enlightenment," precedes individual perceptions as to what it takes to achieve it. The issue with this is that most are individual techniques when in general the truth lies in how that person handles life, i.e. how they think, how they perform deeds and the words they use. Martial arts are a physical discipline, effort and spiritual action necessary to blend the thought, word and deed to effect our physical reality.
San-mitsu explains how a person can increase the body's energy level and capacity by the practice of a martial art. This is emphasized more in the internal arts of China, i..e Chi Gung and Tai Chi Chuan. It is about utilizing the physical to achieve the mental and spiritual.
Our physical efforts use and enhance certain frequencies on a molecular level. Words are the expression of our thoughts. When spoken they to have certain frequencies or vibrations. Our physical actions as to deeds and the perceived actions that are to be viewed as putting thought into action on an every day basis are the most obvious, i.e. body language tends to convey true meaning so that words and thoughts are confirmed as one wholehearted way of present moment living. It is how one sets the example over just using words alone.
San-mitsu is another principle or sub-principle of the foundation we must create on a physical level leading our mental and spiritual toward a more holistic wholehearted approach to martial arts and life.
The characters/ideograms mean, "three mysteries to enlightenment; thought, word and deed; three mysteries (Buddha's body, speech and mind)." The first character means, "three," the second character means, "secrecy; density (pop); minuteness; carefulness."