Sri Aurobindo
Letters of Sri Aurobindo
Volume III - Part 3
You can certainly go on developing the consciousness of the Witness Purusha above, but if it is only a witness and the lower Prakriti is allowed to have its own way, there would be no reason why it [an unquiet and disturbed condition] should ever stop. Many take that attitude – that the Purusha has to liberate itself by standing apart, and the Prakriti can be allowed to go on till the end of the life doing its own business,– it is prārabdha karma; when the body falls away, the Prakriti will drop also and the Purusha go off into the featureless Brahman! This is a comfortable theory, but of more than doubtful truth; I don’t think liberation is so simple and facile a matter as that. In any case, the transformation which is the object of our Yoga would not take place.
The Purusha above is not only a Witness, he is the giver (or withholder) of the sanction; if he persistently refuses the sanction 
to a movement of Prakriti, keeping himself detached, then, even if it goes on for a time by its past momentum, it usually loses its hold after a time, becomes more feeble, less persistent, less concrete and in the end fades away. If you take the Purusha consciousness, it should be not only as the Witness but as the Anumanta, refusing sanction to the disturbing movements, sanctioning only peace, calm, purity and whatever else is part of the divine nature. This refusal of sanction need not mean a struggle with the lower Prakriti; it should be a quiet, persistent, detached refusal leaving unsupported, unassented to, without meaning or justification the contrary action of the nature.