Who else remains in Nirvana when Buddha go back to Samsara | Vajra Pratyeka Buddha

Who else remains in Nirvana when Buddha go back to Samsara (Khi Phật quay lại luân hồi thì niết bàn còn ai không?) | Vajra Pratyeka Buddha “Dear Master, in Nirvana, Buddhas are the same entity. When one Buddha returns to the mundane world, who else remains in Nirvana? A Buddha attains Nirvana, what does solitary Nirvana mean? Although a billion Buddhas attain Nirvana at the same time, a billion Buddhas are the same true entity who is called “Tathagata“. That means we’re actually one entity, rather than two different entities. We’re one entity in fact. But in this illusion, there are different appearances. You must aware of if the differences are real or illusive. The differences appear due to the delusion, so it is an illusion. Why is it illusive? Because these delusive appearances must be interdependent to exist. Like a tree in need of soil, water, sunlight, oxygen, temperature conditions and others; water, soil,