Be still and ask yourself: 'who am I'

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~ How will the mind become quiescent?
By the inquiry 'Who am I?'. The thought 'who am I?' will destroy all other thoughts, and like the stick used for stirring the burning pyre, it will itself in the end get destroyed. Then, there will arise Self-realization.

~ What is the means for constantly holding on to the thought 'Who am I?'
When other thoughts arise, one should not pursue them, but should inquire: 'To whom do they arise?' It does not matter how many thoughts arise. As each thought arises, one should inquire with diligence, "To whom has this thought arisen?". The answer that would emerge would be "To me". Thereupon if one inquires "Who am I?", the mind will go back to its source; and the thought that arose will become quiescent. With repeated practice in this manner, the mind will develop the skill to stay in its source. When the mind that is subtle goes out through the brain and the sense organs, the gross names and forms appear; when it stays in the heart, the names and forms disappear.
Not letting the mind go out, but retaining it in the Heart is what is called "inwardness" (antarmukha). Letting the mind go out of the Heart is known as "externalisation" (bahir-mukha). Thus, when the mind stays in the Heart, the 'I' which is the source of all thoughts will go, and the Self which ever exists will shine. Whatever one does, one should do without the egoity "I". If one acts in that way, all will appear as of the nature of Siva (God).

~ What is the nature of the Self?
What exists in truth is the Self alone. The world, the individual soul, and God are appearances in it. like silver in mother-of-pearl, these three appear at the same time, and disappear at the same time. The Self is that where there is absolutely no "I" thought. That is called "Silence". The Self itself is the world; the Self itself is "I"; the Self itself is God; all is Siva, the Self.

From the book: Who Am I? (Nan Yar?), The Teachings of Bhagavan Sri Ramana Maharshi.
Translation by Dr. T. M. P. MAHADEVAN From the original Tamil.