Ramana Maharishi from Who am I

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’ (bahirmukha). 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.