The traditional Eastern triad of earth, man, heaven can be translated to what, how, and why, or object, verb, and subject (taken primarily as as the source of valuation).
The trigrams describe varying states (yang, changing yang, yin, changing yin) each stratum (or yao, in the language of trigrams) can take which determines the quality of a given situation. A situation comprises a subject situated amidst objects of varying relationship to the subject. The state of each stratum can be unitary or fragmentary (unitary corresponding to yang, disintegrating/diverging corresponding to changing yang, fragmentary corresponding to yin, integrating/converging corresponding to changing yin).
The value of the trigrams lies in the fact that the situations are intrinsically gestalts that are not easy to analyze, because each part of the situation modifies the whole in non-obvious ways. The modification seems to be caused by what is modified, where what is modified generally reflects a change originating elsewhere. For instance, if the meaning of a situation (heaven/why/subject) is disintegrating, this change may be felt most distinctly as doubts around the practical response (man/how/verb) and the objects concerned (earth/what/object) in the form of change in relevance and relation among the entities involved in the situation. Conversely, if heaven is integrating the change may manifest as emerging practical resolve and as clarity in regard to the relevant entities and how they connect. (I may write more on this later.)
Another thing I want to record before I forget: the permutations of yin and yang in each yao create situational gestalts, each with distinct character. The “Securing Reality” post I made last month was a first attempt to summarize those situational gestalts.