Substance and Function (Ti Yong)

One chart, two questions

Every chart has a substance — the thing that must be kept whole — and a function — the thing it is meant to do. The mistake is to answer with only one of them: to defend an element because it is the day master, or to chase an element because it is 'useful', without asking whether the two agree. The chapter's rule is procedural: decide what must be supported and what must be restrained, and check that the support and restraint actually fit this chart.