Sri Ramana’s central teaching
Sri Ramana’s central teaching is: Self-inquiry. Instead of wanting to know this and that, seek to know the Self. Ask ‘Who am I?’ instead of asking about a hundred other things. Self-inquiry ought to be the easiest of all tasks. But it seems to be the most difficult because we have become strangers to our Self. What one has to do is simple - to abide as the Self. This is the ultimate Truth. This is one’s eternal, natural, inherent state. On account of ignorance we identify ourselves with the not-I.
The most subtle of all these identifications is with the ego. Let us search for the root of the ego. Where from does this pseudo-I arise? At the end of this quest we shall find that the ego disappears letting the eternal Self shine. So the best discipline is the inquiry: ‘Who am I?’ This is the greatest japa. This is the true pranayama. The thought ‘I am not the body’ (naham) is exhalation (rechaka); the inquiry ‘Who am I?’ (koham) is inhalation (puraka); the realization ‘I am He’ (soham) is retention of breath (kumbhaka). The fruit of Self-inquiry is the realization that the Self is all, and that there is nothing else. For those who follow this method no other sadhana is necessary. But even those who adopt the discipline of devotion (bhakti) reach the same goal. If one surrenders one’s ego to either the Guru or God, one realizes the Self.
(from Talks with Sri Ramana Maharshi, Foreword by T. M. P. Mahadevan)