Sri Aurobindo
Bases of Yoga
Bases of Yoga
If the difficulty in meditation is that thoughts of all kinds come in, that is not due to hostile forces but to the ordinary nature of the human mind. All sadhaks have this difficulty and with many it lasts for a very long time. There are several ways of getting rid of it. One of them is to look at the thoughts and observe what is the nature of the human mind as they show it but not to give any sanction and to let them run down till they come to a standstill — this is a way recommended by Vivekananda in his Rajayoga. Another is to look at the thoughts as not one’s own, to stand back as the witness Purusha and refuse the sanction — the thoughts are regarded as things coming from outside, from Prakriti, and they must be felt as if they were passers-by crossing the mind-space with whom one has no connection and in whom one takes no interest. In this way it usually happens that after a time the mind divides into two, a part which is the mental witness watching and perfectly undisturbed and quiet and a part which is the object of observation, the Prakriti part in which the thoughts cross or wander. Afterwards one can proceed to silence or quiet the Prakriti part also. There is a third, an active method by which one looks to see where the thoughts come from and finds they come not from oneself, but from outside the head as it were; if one can detect them coming, then, before they enter, they have to be thrown away altogether. This is perhaps the most difficult way 
and not all can do it, but if it can be done it is the shortest and most powerful road to silence.