The teachings of the five elements and the five phases of transformation (wǔxíng) is a Daoist theory for describing nature. It searches for regularities according to which dynamic transformation processes take place within the realm of the living. The five elements Wood, Earth, Water, Fire and Metal are derived from nature and stand for abstract properties.
How the trigrams of the I Ching are assigned to the five phases of transformation in the present interpretation model is explained in more detail here: Trigrams, Elements, Functional Circuits
