1). What is the opinion of Shri Shankara on Samadhi.
What Śaṅkara says is that duality, such as the fundamental distinction between subject and object, is obliterated in deep sleep and in samādhi, as well as in other conditions such as fainting, but duality is only temporarily obliterated for it reappears when one awakes from sleep or regains consciousness after fainting, and it also reappears when the yoga arises from samādhi. The reason why duality persists is because false knowledge (mithyājñāna) has not been removed. It is evident from this brief statement that Śaṅkara does not consider the attainment of samādhi to be a sufficient cause to eradicate false knowledge, and, according to Śaṅkara, since false knowledge is the cause of bondage, samādhi cannot therefore be the cause of liberation.
Shri Shankara says that if liberation is an effect of some kind of action, then liberation would have a beginning and would be time-bound and hence noneternal, and that such a consequence would go against the whole tradition that teaches that liberation is eternal. Śaṅkara’s view is that liberation is nothing but being Brahman, and that is one’s inherent condition, although it is obscured by ignorance. He says that the whole purpose of the Upaniṣads is just to remove duality, which is a construct of ignorance
Shri Śaṅkara present the Ātman-Brahman as a goal to be reached. On the contrary, his approach is that the Ātman-Brahman is not something to be acquired since it is one’s own nature, and one’s own nature is not something that can be attained. This approach has its corollary in his method of negation: the removal of superimpositions in order to discover what is already there, although concealed as it were by all sorts of false identifications based ultimately upon the ignorance of who we really are. Such an approach is different from that of the classical Yoga of the Yogasūtras, where a goal is presented in terms of nirvikalpasamādhi, which one has to achieve in order to gain liberation. That Śaṅkara’s method is one of negation in order to “reveal the ever revealed” through negation – neti, neti, neti … through the process of Viveka and vairagya.
Q2) What is opinion of Shri Ramana Maharshi on Samadhi ?
The state in which the unbroken experience of existence-consciousness is attained by the still mind, alone is samadhi. That still mind which is adorned with the attainment of the limitless supreme Self, alone is the reality of God.
When the mind is in communion with the Self in darkness, it is called nidra [sleep], that is, the immersion of the mind in ignorance. Immersion in a conscious or wakeful state is called samadhi. Samadhi is continuous inherence in the Self in a waking state. Nidra or sleep is also inherence in the Self but in an unconscious state. In sahaja samadhi the communion is continuous.
Question : What are kevala nirvikalpa samadhi and sahaja nirvikalpa samadhi?
Ramana Maharshi :The immersion of the mind in the Self, but without its destruction, is kevala nirvikalpa samadhi. In this state one is not free from vasanas and so one does not therefore attain mukti. Only after the vasanas have been destroyed can one attain liberation.
Q3 ). When can one practice sahaja samadhi ?
Ramana Maharshi : Even from the beginning. Even though one practises kevala nirvikalpa samadhi for years together, if one has not rooted out the vasanas one will not attain liberation.
Q4) May I have a clear idea of the difference between savikalpa and nirvikalpa?
Ramana Maharshi : Holding on to the supreme state is samadhi. When it is with effort due to mental disturbances, it is savikalpa. When these disturbances are absent, it is nirvikalpa. Remaining permanently in the primal state without effort is sahaja.
Q5) Is nirvikalpa samadhi absolutely necessary before the attainment of sahaja?
Ramana Maharshi : Abiding permanently in any of these samadhis, either savikalpa or nirvikalpa, is sahaja [the natural state].
Q6). What is body-consciousness?
It is the insentient body plus consciousness. Both of these must lie in another consciousness which is absolute and unaffected and which remains as it always is, with or without the body-consciousness. What does it then matter whether the body-consciousness is lost or retained, provided one is holding on to that pure consciousness? Total absence of body-consciousness has the advantage of making the samadhi more intense, although it makes no difference to the knowledge of the supreme.
Light of The Self Foundation 