妙法蓮華經玄義 2.74

2.74

○標章者，云何境妙？謂十如、因緣、四諦、三諦、二諦、一諦等。是諸佛所師，故稱境妙。

As for presenting the headings: what is the subtlety of objects? It refers to the ten suchnesses, causes and conditions, the four noble truths, the three truths, the two truths, the one truth, and so forth. These are the teachers of all buddhas, and therefore it is called the subtlety of objects.