Sri Aurobindo
Letters of Sri Aurobindo
Volume III - Part 3
It seems that you do not pay sufficient attention to the instructions that are sent to you from here. You were specially warned 
not to allow anything to take possession of you. But in relating one of your experiences repeated for several days you speak of something that was taking possession of you, even obliging you to make incoherent noises, and yet you say you do not know whether it was good or bad or what kind of force it was! It is evident from your description that it was a vital force trying to take violent possession of the body. Nothing can be more dangerous than to allow this kind of loss of control and intrusion of an alien influence. In your present condition of ignorance, the vital being not yet sufficiently open, the psychic not yet sufficiently awake, a hostile power can easily intrude and pass itself off as the divine Force. Remember that no personality and no power is to be allowed to possess you. The divine Force will not act in this way; it will work first to purify, to widen and enlighten and transform the consciousness, to open it to Light and Truth, to awaken the heart and the psychic being. Only afterwards will it take gradual and quiet control through a pure and conscious surrender.