Through my study of Taoism in the Healing Tao system of Mantak Chia, one of the major learning tools we were exposed to was the use of the Correspondences of the 5 Elements. Although a later development in Chinese history as compared to Yin-Yang theory, it nevertheless developed quite early, first appearing in the Yellow Emperor's Classic of Internal Medicine (Huang Di Nei Jing Su Wen). In this seminal work on Chinese medicine, an incredible array of information was divided into five-fold systems, with their sub-components being related to the five elements of Fire, Water, Earth, Metal and Wood, based upon the nature of their attributes and how they related to each other.

5 Element theory is an extensive and very important method to Traditional Chinese medicine, of dividing knowledge into sets of 5 polarities, and establishing correspondences between the various elements within the system. Indeed, 5 Element theory could be correctly labelled "Quintuplex Unity Theory", as the method in which information is reduced to polarities and then related across the board, through the notion of Unity, is virtually identical to that of Triplex Unity Theory.

In fact, it is my suspicion that those ancients who formulated the Correspondences the 5 Elements, knew and understood the basic function of Triplex Unity in the very beginning. Triplex Unity Theory was simply a tool which they took and applied to the field of medicine, expanded upon it, and developed it to the extensive system it is, one that has largely remained unchanged for more than 2000 years.