Explain Buddha nature

Buddha-nature is a doctrine important for many schools of Mahayana Buddhism. The Buddha Nature is taught to be a truly real, but internally hidden, eternal potency element within the purest depths of the mind, present in all sentient beings, for awakening and becoming a Buddha. In some Mahayana sutras it is equated with the eternal Buddhist Self, Essence. However, Nagarjuna, the founder of Madhyamaka, presents a view that states that Buddha-nature is empty-nature.

The Buddha-nature insist, however, that what the Buddha-nature is empty of is not its own ever-enduring reality but impermanence, impurity, moral defects, and suffering - in other words, the painful constrictions and imperfection of samsara.  The Buddha-nature is also frequently stressed in the sutras which expound this Buddha Element. The Srimala Sutra, for example, says: "The Tathagatagarbha is not born, does not die, and does not transfer does not arise. It is beyond the sphere of the characteristics of the compounded, it is permanent, stable and changeless." The development of the Buddha-nature doctrine is closely related to that of tathagatagarbha. In the "Anunatva-Apurnatva-Nirdesa" sutra the Buddha links the tathagatagarbha to the Dharmadhatu  and to essential being, stating: "What I call 'be-ing'  is just a different name for this permanent, stable, pure and unchanging refuge that is free from arising and cessation, the inconceivable pure Dharmadhatu." Buddha dhatu absolutely all beings without exception, even icchantikas will eventually attain liberation and become Buddhas. Buddha nature is always present in us all times and in all beings but is obscured from worldly vision by the screening effect of negative mental afflictions within each being.