Even when extraneous thoughts sprout up during such enquiry, do not seek to complete the rising thought, but instead, deeply enquire within, 'To who has this thought occurred?' No matter how many thoughts thus occur to you, if you would with acute vigilance enquire immediately as and when each individual thought arises to whom it has occurred, you would find it is to 'me'. If then you enquire 'Who am I?' the mind gets introverted and the rising thought also subsides. In this manner as you persevere more and more in the practice of self-enquiry, the mind acquires increasing strength and power to abide in its Source.

~ Sri Ramana Maharshi, Who Am I? - Nan Yar?