Sri Aurobindo
Letters of Sri Aurobindo
01. The Object of Integral Yoga
To find the Divine is indeed the first reason for seeking the spiritual Truth and the spiritual life; it is the one thing indispensable and all the rest is nothing without it. The Divine once found, to manifest Him,– that is, first of all to transform one’s own limited consciousness into the Divine Consciousness, to live in the infinite Peace, Light, Love, Strength, Bliss, to become that in one’s essential nature and, as a consequence, to be its vessel, channel, instrument in one’s active nature. To bring into activity the principle of oneness on the material plane or to work for humanity is a mental mistranslation of the Truth – these things cannot be the first true object of spiritual seeking. We must find the Self, the Divine, then only can we know what is the work the Self or the Divine demands from us. Until then our life and action can only be a help or means towards finding the Divine and it ought not to have any other purpose. As we grow in the inner consciousness, or as the spiritual Truth of the Divine grows in us, our life and action must indeed more and more flow from that, be one with that. But to decide beforehand by our limited mental conceptions what they must be is to hamper the growth of the spiritual Truth within. As that grows we shall feel the Divine Light and Truth, the Divine Power and Force, the Divine Purity and Peace working within us, dealing with our actions as well as our consciousness, making use of them to reshape us into the Divine Image, removing the dross, substituting the pure gold of the Spirit. Only when the Divine Presence is there in us always and the consciousness transformed, can we have the right to say that we are ready to manifest the Divine on the material plane. To hold up a mental ideal or principle and impose that 
on the inner working brings the danger of limiting ourselves to a mental realisation or of impeding or even falsifying by a halfway formation the true growth into the full communion and union with the Divine and the free and intimate outflowing of His will in our life. This is a mistake of orientation to which the mind of today is especially prone. It is far better to approach the Divine for the Peace or Light or Bliss that the realisation of Him gives than to bring in these minor things which can divert us from the one thing needful. The divinisation of the material life also as well as the inner life is part of what we see as the Divine Plan, but it can only be fulfilled by an outflowing of the inner realisation, something that grows from within outwards, not by the working out of a mental principle.
You have asked what is the discipline to be followed in order to convert the mental seeking into a living spiritual experience. The first necessity is the practice of concentration of your consciousness within yourself. The ordinary human mind has an activity on the surface which veils the real Self. But there is another, a hidden consciousness within behind the surface one in which we can become aware of the real Self and of a larger deeper truth of nature, can realise the Self and liberate and transform the nature. To quiet the surface mind and begin to live within is the object of this concentration. Of this true consciousness other than the superficial there are two main centres, one in the heart (not the physical heart, but the cardiac centre in the middle of the chest), one in the head. The concentration in the heart opens within and by following this inward opening and going deep one becomes aware of the soul or psychic being, the divine element in the individual. This being unveiled begins to come forward, to govern the nature, to turn it and all its movements towards the Truth, towards the Divine, and to call down into it all that is above. It brings the consciousness of the Presence, the dedication of the being to the Highest and invites the descent into our nature of a greater Force and Consciousness which is waiting above us. To concentrate in the heart centre with the offering of oneself to the Divine and the aspiration for this inward opening and for the Presence in the heart is the first way and, if it can be done, the natural beginning; for its result 
once obtained makes the spiritual path far more easy and safe than if one begins the other way.
That other way is the concentration in the head, in the mental centre. This, if it brings about the silence of the surface mind, opens up an inner, larger, deeper mind within which is more capable of receiving spiritual experience and spiritual knowledge. But once concentrated here one must open the silent mental consciousness upward to all that is above mind. After a time one feels the consciousness rising upward and in the end it rises beyond the lid which has so long kept it tied in the body and finds a centre above the head where it is liberated into the Infinite. There it begins to come into contact with the universal Self, the Divine Peace, Light, Power, Knowledge, Bliss, to enter into that and become that, to feel the descent of these things into the nature. To concentrate in the head with the aspiration for quietude in the mind and the realisation of the Self and Divine above is the second way of concentration. It is important, however, to remember that the concentration of the consciousness in the head is only a preparation for its rising to the centre above; otherwise, one may get shut up in one’s own mind and its experiences or at best attain only to a reflection of the Truth above instead of rising into the spiritual transcendence to live there. For some the mental concentration is easier, for some the concentration in the heart centre; some are capable of doing both alternately - but to begin with the heart centre, if one can do it, is the more desirable.
The other side of discipline is with regard to the activities of the nature, of the mind, of the life-self or vital, of the physical being. Here the principle is to accord the nature with the inner realisation so that one may not be divided into two discordant parts. There are here several disciplines or processes possible. One is to offer all the activities to the Divine and call for the inner guidance and the taking up of one’s nature by a Higher Power. If there is the inward soul-opening, if the psychic being comes forward, then there is no great difficulty – there comes with it a psychic discrimination, a constant intimation, finally a governance which discloses and quietly and patiently removes all imperfections, brings the right mental and vital movements and 
reshapes the physical consciousness also. Another method is to stand back detached from the movements of the mind, life, physical being, to regard their activities as only a habitual formation of general Nature in the individual imposed on us by past workings, not as any part of our real being; in proportion as one succeeds in this, becomes detached, sees mind and its activities as not oneself, life and its activities as not oneself, the body and its activities as not oneself, one becomes aware of an inner Being within us – inner mental, inner vital, inner physical – silent, calm, unbound, unattached which reflects the true Self above and can be its direct representative; from this inner silent Being proceeds a rejection of all that is to be rejected, an acceptance only of what can be kept and transformed, an inmost Will to perfection or a call to the Divine Power to do at each step what is necessary for the change of the Nature. It can also open mind, life and body to the inmost psychic entity and its guiding influence or its direct guidance. In most cases these two methods emerge and work together and finally fuse into one. But one can begin with either, the one that one feels most natural and easy to follow.
Finally, in all difficulties where personal effort is hampered, the help of the Teacher can intervene and bring about what is needed for the realisation or for the immediate step that is necessary.