Sri Aurobindo
Letters of Sri Aurobindo
Volume IV - Part 3
The depression coming on you in sleep must have been due to one of two causes. It might have been the trace left by an unpleasant experience in some disagreeable quarter of the vital world and there are places in plenty of that kind there. It can 
hardly have been an attack, for that would surely have left a more distinct impression of something having happened, even if there was no actual memory of it; but merely to enter into certain places or meet their inhabitants or enter into contact with their atmosphere can have, unless one is a born fighter and takes an aggressive pleasure in facing and conquering these ordeals, a depressing and exhausting effect. If that is the cause, then it is a question of either avoiding these places, which can be done by an effort of will, once one knows that it is this which happens, or putting around you a special protection against the touch of that atmosphere. The other possible cause is a plunge into a too obscure and subconscient sleep – that has sometimes the effect you describe. In any case, do not allow yourself to be discouraged when these things happen; they are common phenomena one cannot fail to meet with as soon as one begins to penetrate behind the veil and touch the occult causes of the psychological happenings within us. One has to learn the causes, note and face the difficulty and always react – never accept the depression thrown on one, but react as you did the first time. If there are always forces around which are concerned to depress and discourage, there are always forces above and around us which we can draw upon,– draw into ourselves to restore, to fill up again with strength and faith and joy and the power that perseveres and conquers. It is really a habit that one has to get of opening to these helpful forces and either passively receiving them or actively drawing upon them – for one can do either. It is easier if you have the conception of them above and around you and the faith and the will to receive them – for that brings the experience and concrete sense of them and the capacity to receive at need or at will. It is a question of habituating your consciousness to get into touch and keep in touch with these helpful forces – and for that you must accustom yourself to reject the impressions forced on you by the others, depression, self-distrust, repining and all similar disturbance.
As for the actual mastery of a situation by occult powers, it can only come by use and experiment – as one develops strength by exercises or develops a process in the laboratory by finding out through the actual use of a power how it can and ought to be applied to the field in which it operates. It is of no use waiting for the strength before one tries; the strength will come with repeated trials. Neither must you fear failure or be discouraged by failure – for these things do not always succeed at once. These are things one has to learn by personal experiences, how to get into touch with the cosmic forces, how to relate or equate our individual action with theirs, how to become an instrument of the Master Consciousness which we call the Divine.
There is something a little too personal in your attitude – I mean the insistence on personal strength or weakness as the determining factor. After all, for the greatest as for the smallest of us our strength is not our own but given to us for the game that has to be played, the work that we have to do. The strength may be formed in us, but its present formation is not final,– neither formation of power nor formation of weakness. At any moment the formation may change – at any moment one sees, especially under the pressure of Yoga, weakness changing into power, the incapable becoming capable, suddenly or slowly the instrumental consciousness rising to a new stature or developing its latent powers. Above us, within us, around us is the All-Strength and it is that that we have to rely on for our work, our development, our transforming change. If we proceed with the faith in the work, in our instrumentality for the work, in the Power that missions us, then in the very act of trial, of facing and surmounting difficulties and failures, the strength will come and we shall find our capacity to contain as much as we need of the All-Strength of which we grow more and more perfect vessels.