Anūnatvāpurnatvanirdeśa

[12] The first part of the AAN outlines various wrong views (mithyā-dr̥ṣṭi) which prevent sentient beings from obtaining knowledge of the ultimate truth.

[13] The Sutra of Non-increase and Non-decrease explains that this is because there is only a one realm or domain, a single element of beings, the ekadhātu (Ch: 一界), also termed the *ekadharmadhātu (一法界).

[13][15] This one domain is identical to both Buddhahood (i.e. the nirvāṇa-dhātu) and saṃsāra (the realm of cyclical suffering, i.e. sattvadhātu), both which are non-dual and indivisible.

According to Silk, in the AAN, the term dhātu has at least a bivalent sense, referring to both a "realm" (i.e. the cosmos) and a "quintessence" (the intrinsic or central constituent of something).

According to the AAN, neither sentient beings, disciples or solitary Buddhas can know this ultimate reality directly, they can only access it through faith.

[Despite] the insight possessed by all auditors and lone buddhas, Śāriputra, with respect to this purport, they can only have faith; they are not able to know, see or examine it in accord with reality.

89-92) The sutra goes on to equate this single reality with the ultimate truth (paramārtha-satya), with buddha-nature (tathāgatagarbha), with the Dharmakaya (Dharma body of the Buddha) and with the “originally pure mind” (prakṛtipariśuddhacitta).

[19][20] The Sutra of Non-increase and Non-decrease states: As I have expounded, Śāriputra, the meaning of the dharma-body is inseparable from, indivisible from, not cut-off from, not different from the inconceivable qualities definitive of a buddha, greater in number than the sands of the Ganges, [namely,] the merits and insight of a tathāgata.

96-98 §11, 12)This idea is an important source for the Ratnagotravibhāga's fifth vajra point, and this text quotes the Sutra of Non-increase and Non-decrease on this topic.

This inseparability is exemplified in the sutra with the examples of a light (aloka) and a precious gem (mani), both of which became influential similes in the Mahayana tradition.

[citation needed] According to the Sutra of Non-increase and Non-decrease, the buddha-nature - dharmakaya is also the eternal ground or basis of all things or dharmas (phenomena).

[citation needed] The dharma-body, the ultimate reality, is also said to be that which is “hidden within a sheath of countless defilements” and which undergoes rebirth in saṃsāra.

[10] According to the AAN, there are three ways the single reality manifests, which according to Silk are "nothing more than modalities of the embryo of the tathāgatas, variously related to ultimate Reality":[22] As such, buddhas, bodhisattvas and sentient beings are not different in terms of their essential nature (their only difference is in the relative state of the covering defilements) and are all therefore not ultimately subject to increase or decrease.

While there are three different aspects or modalities of this unitary reality, they are all one realm, a single essence, which is the common ground for all things.

[25] Christopher Jones similarly writes that this sutra is defending an "absolute principle," which is the dharmakāya filled with buddha qualities.