Dr. Stone's entire world-view is built on the concept of Three Principles and Five Elements. The Three Principles concept refers to Yang-Yin-Neutral (or Tao), being the continuous rhythmic circuit-flow of energy, from spirit to matter and back, that is the basis of all phenomena in the ancient Himalayan wisdom traditions as well as in modern physics. The Five Elements (Ether, Air, Fire, Water, Earth) concept refers to the stages of materialization, from subtle to dense and back, particularly in the context of the five chakras or energy transformers along the spine.
For whatever reasons, Dr. Stone was not consistent in his usage of these terms. There are places where this problem is very clear, and other places where there is some uncertainty.
To avoid this confusion, Dr. Stone's "Fiery Principle" is more commonly referred to as "Yang," his "Watery Principle" is referred to as "Yin," and his "Airy Principle" as "Neutral" or "Tao."
Within DigitalDrStone, the editors attempt to give [in brackets]1 unified updated language interpreting what Dr. Stone meant when he used the terms "Principle" or "Element" based on modern understanding. It should be recognized that there is openness, indeed eagerness, for further scholarly debate about the correctness of these interpretations.
1 and footnotes