Huayan thought presents the non‑obstruction of principle and phenomena by refusing to separate ultimate reality from the concrete world of events and things. Principle (li) is described as emptiness or suchness, the undifferentiated Buddha‑nature that underlies all, while phenomena (shi) are the myriad particular manifestations that arise through dependent origination. Rather than standing in opposition, these two are seen as completely interpenetrating aspects of a single reality: emptiness enables manifestation, and manifestation expresses emptiness. Emptiness does not erase the distinctiveness of things, and the distinctiveness of things never departs from emptiness. In this way, every particular event is simultaneously a conditioned occurrence and a full embodiment of the absolute.

This vision is articulated systematically in the teaching of the Four Dharmadhātus. One can contemplate reality as principle alone, as phenomena alone, as the non‑obstruction between principle and phenomena, and finally as the non‑obstruction among phenomena themselves. The third level, the dharmadhātu of non‑obstruction between principle and phenomena, makes explicit that there is no gap between the ultimate and the relative: each phenomenon is nothing other than principle, and principle is nowhere apart from phenomena. The fourth level extends this insight, suggesting that because each phenomenon fully embodies principle, phenomena themselves mutually interpenetrate without hindrance.

Huayan masters turned to vivid images to make this subtle vision intelligible. The Net of Indra portrays the cosmos as an infinite web of jewels, each jewel reflecting all the others without limit. Each jewel is a distinct phenomenon, yet each also contains and expresses the whole net; its very particularity is the mode through which the universal principle shines. Likewise, the analogy of waves and water shows how phenomena and principle are distinguishable yet inseparable: waves arise and cease, but never depart from water, and water’s nature does not obstruct the arising of waves. In ordinary experience, this means that the absolute is not found apart from daily life; it is fully present in every thought, action, and encounter, if seen without dividing principle from the living field of phenomena.