This text describes a cosmos of infinite realms upon realms, mutually containing each other. The vision expressed in this work was the foundation for the creation of the Huayan school of Chinese Buddhism, which was characterized by a philosophy of interpenetration. Hua-yen is known as Kegon in Japan.
The sutra was written in stages, beginning from at least 500 years after the death of the Buddha. Two full Chinese translations of the Avatamsaka Sutra were made. Fragmentary translation probably began in the second century CE, and the famous Ten Stages Sutra (十地經), often treated as an individual scripture, was first translated in the third century. The first complete Chinese version was completed by Buddhabhadra around 420, and the second by around 699. There is also a translation of the Gandavyuha by Prajñā around 798. The second translation includes more sutras than the first, and the Tibetan translation, which is still later, includes even more. Scholars conclude that sutras were being added to the collection.
The sutra, among the largest in the Buddhist canon, contains 40 chapters of somewhat disparate topics, though with some overarching themes:
Two of the chapters serve as sutras in their own right, and have been cited in the writings of many Buddhists in East Asia.
Chapter 26, the Dasabhumika Sutra or Sutra of the Ten Stages details the ten stages, or bhūmi, of development a bodhisattva must undergo to attain supreme enlightenment. The ten stages are also depicted in the Lankavatara Sutra. The sutra also touches on the subject of the development of the aspiration for Enlightenment.
The last chapter of the Avatamsaka also circulates as a separate text known as the Gandavyuha Sutra. The Gandavyuha Sutra details the journey of the youth Sudhana, who undertakes a pilgrimage at the behest of the bodhisattva Manjushri. Sudhana will converse with 52 masters in his quest for enlightenment. The ante-penultimate master of Sudhana's pilgrimage is Maitreya. It is here that Sudhana encounters "The Tower of Maitreya," which along with "Indra's net" is one of the most startling metaphors of the infinite to emerge in the history of literature across cultures.
The penultimate master that Sudhana visits is the bodhisattva Manjushri. Thus, one of the grandest, and most fully loaded with perennial symbolism, of pilgrimages comes to its conclusion by first revisiting where it began. The Gandavyhua suggests that with a subtle shift of perspective we may come to see that the enlightenment that the pilgrim so fervently sought was not only with him at every stage of his journey, but as well before it kick off; that enlightenment is not 'something to be gained' since, to begin with, the pilgrim (aka all of us) never departed from 'it'.
The final master that Sudhana visits is the bodhisattva Samantabhadra, who teaches him that wisdom is only for the sake of putting it into practice, that is, in benefiting all living beings all over the universe according to conditions.