According to the Great Madhyamaka tradition, there is sutra zhentong and tantra zhentong. In accord with sutra zhentong, the Great Madhyamaka system of the Jonang emphasizes Shakyamuni’s 3rd “turning” or final set of discourses. This understanding of mind and reality seeks to reconcile the paradox of a lack of any permanent essence (sunyata, emptiness), and that of an ever-abiding permanent enlightened essence (tathagatagarbha, buddha-nature).
“Zhentong,” (gzhan stong, “shentong”) “extrinsic emptiness” or “other-emptiness” is a view of how the ultimate nature of reality is free from or empty of everything “other” than its absolute nature. In other words, a zhentong view understands how one’s own enlightened essence is empty of everything false in superficial relative reality.
Zhentong as a view for meditation practice regards relative reality as empty of its own intrinsic existence. This emptiness of inherent substance or “rangtong” is considered to be solely the nature of relative reality while ultimate reality is understood to be empty of everything other than itself. Accordingly, transient tangible experiences remain devoid of inherent substance as the boundless luminous nucleus of Buddhahood within all beings remains intangible and invariant.
This enlightened essence is regarded as an indwelling permanently pure nature of awareness. It is the mind devoid of its distorted perceptions. Likened to an embryo or a womb, this essence (garbha) provides the potentiality for living beings to be reborn into completely awakened Buddhas.