The doctrine for which the Avatamsaka Sutra is best remembered is usually summarized through a single image: Indra's Net, a net stretching infinitely in every direction with a brilliant jewel tied at each knot, each jewel reflecting every other jewel in the net and, within each reflection, reflecting all the other reflections again without end. The image is the sutra's way of describing what its later interpreters in the Chinese Huayan school called the unobstructed interpenetration of all phenomena, the claim that every particular thing in the universe contains and is contained by every other thing, so that no phenomenon stands apart as an isolated cause or effect. This teaching is set within an unusual narrative frame.
Unlike sutras built around Shakyamuni Buddha teaching an audience in ordinary speech, the Avatamsaka presents its central figure, the cosmic buddha Vairocana, as remaining in profound meditative absorption throughout almost the entire text, never speaking the doctrine directly; instead, bodhisattvas empowered by his presence deliver the teaching in his stead, and the various assemblies described in the sutra are understood as visionary manifestations of Vairocana's own enlightened awareness rather than events in an ordinary place.
Huayan patriarchs in Tang dynasty China, working from Siksananda's translation, built a systematic philosophy on this vision, and the school's influence on Chinese Buddhist thought outlasted its own institutional decline, shaping how later Chan teachers described the mutual interpenetration of a single moment of practice and the whole of enlightenment.