Sri Aurobindo relates the story of his own practice of Yoga and the technique of rejecting the thoughts as they entered from outside — thereby creating a total silence of the mind. The silencing of the mind represents the third step in the process of concentration. “This may be done by various ways; one is to stand back from the mental action altogether not participating in but simply watching it until, tired of its unsanctioned leaping and running, it falls into an increasing and finally an absolute quiet.” This particular method is recommended by Swami Vivekananda in his lectures on Raja Yoga, with some variations that may include monitoring and creating an equal, even flow of the breath, and thereby stilling the mind-stuff (chitta) from its incessant action.
There is also another more active technique, which is the one utilized by Sri Aurobindo himself in this regard: “Another is to reject the thought-suggestions, to cast them away from the mind whenever they come and firmly to hold the peace of the being which really and always exists behind the trouble and riot of the mind.” It may be noted that Sri Aurobindo observed that we do not “create” the thoughts in our own mind, but they come to us from outside and can be treated as external forms to be rejected before they seize hold of and modify the mind-stuff.
“When this secret peace is unveiled, a great calm settles on the being and there comes usually with it the perception and experience of the all-pervading silent Brahman, everything else at first seeming to be mere form and eidolon. On the basis of this calm everything else may be built up in the knowledge and experience no longer of the external phenomena of things but of the deeper truth of the divine manifestation.”
Sri Aurobindo recounts the remarkable experience of acting, speaking, writing, from the basis of the silent mind once the basic result had been achieved using this method.
Sri Aurobindo, The Synthesis of Yoga, Part Two: The Yoga of Integral Knowledge, Chapter 4, Concentration, pp. 309-310