Advaita Bodha Deepika is a traditional text and a masterpiece, summarising the methods and techniques of advaita vedanta. It was a favourite text of Sri Ramana Maharshi and was often recommended by him. Here is what it says about how to attain liberation, the following is from Chapter 3:
17…Master: With complete stillness of mind, samsara will disappear root and branch. Otherwise there will be no end to samsara, even in millions of aeons (Kalpakotikala).
18. Disciple: Cannot samsara be got rid of by any means other than making the mind still?
M: Absolutely by no other means; neither the Vedas, nor the shastras nor austerities, nor karma, nor vows, nor gifts, nor recital of scriptures of mystic formulae (mantras), nor worship, nor anything else, can undo the samsara. Only stillness of mind can accomplish the end and nothing else.
19. D: The scriptures declare that only Knowledge can do it. How then do you say that stillness of the mind puts an end to samsara?
M: What is variously described as Knowledge, Liberation, etc., in the scriptures, is but stillness of mind.
D: Has any one said so before?
20 M: Sri Vasishta had said…
Beloved Ramana Maharshi says the same in Guru Vachaka Kovai, verse 141:
All the jnana* scriptures that teach the way to redemption proclaim in unison that restraining and stilling the mind is the best means for liberation. This is also emphasised by jnanis*.
If, after a certain amount of study, one knows this to be the inner purport of the scriptures, one should then direct ones whole effort towards that [practice]. What is the use of continuously studying more and more scriptures without doing this?
*Jnana, literally meaning knowledge, refers to the teachings of spiritual liberation, whereas jnani, literally ‘knower’, refers to the spiritually liberated sage.
In Ramana’s ‘Who am I?’, the question as to the nature of Jnana arises and is simply answered:
Questioner: What is wisdom-insight (jnana-drsti)?
Ramana Maharshi: Remaining quiet is what is called wisdom-insight.
The Katha Upanishad states the same, in verse 2.3.10:
When the five organs of perception become still, together with the mind, and the intellect ceases to be active: that is called the Supreme State [Brahman].
The Advaitic giant, Sri Gaudapada, writes in his Mandukya Karika:
‘The controlled mind is verily the fearless Brahman’ Chapter 3, verse 35
And in verse 37 of the same chapter he writes:
[Atman is] beyond all expression by words and beyond all acts of mind; It is all peace, eternal effulgence free from activity and fear and attainable by samadhi’ Chapter 3, verse 37