The following (from Letters on Yoga vol. I pp.271-275) is from a letter to a disciple who - one may presume - inquired about the "pure I" (it is unfortunate the originals have been lost, since the replies on their own often seem out of context). I'm repeating it here because it covers a wide range of important topics. page numbers [thus]
[Letters on Yoga vol. I p.271] Well, it is a little difficult to explain. Perhaps the best thing is to break up my answer into a number of separate statements, for the whole thing has got too complicated to do otherwise.
1. It is impossible to equate my conception or experience of the Jivatman with the pure "I" of the Adwaita, by which you mean, I suppose, something which says, "I am He" and by that perception merges itself into the Brahman. According to the Adwaita of the Mayavadins this Jivatman, like the Ishwara himself, is simply an appearance of the Brahman in illusory Maya. There is no Ishwara, Lord of the world, because there is no world -except in Maya; so too there is no Jivatman, only the Paramatman illusorily perceived as an individual self by the lower (illusory) consciousness in Maya. Those, on the other hand, who wish to unite with the Ishwara, regard or experience the Jiva either as a separate being dependent on the Ishwara or as something one in essence with him, yet different, but this difference like the essential oneness is eternal-and there are also other ideas of the Jivatman and its relation to the Divine or Supreme. So this pure "I", if that is how it is to be described, presents itself differently, in different aspects, one may say, to different people. If you ask why, I refer you to my answer to X. The overmind presents the truth of things in all sorts of aspects and mind, even the spiritual mind, fastens on one or the other as the very truth, the one real truth of the matter. It is the mind that makes these differences, but that does not matter, because, through its own way of seeing and experiencing the soul or individualised consciousness or whatever you may like to call it, the mental being-goes where it has to go. I hope this much is clear as the first step in the matter.
2. I do not dispute at all the fact that one can realise the Self, the Brahman or the Ishwara without going into the overhead regions, the dynamic spiritual planes, or stationing oneself permanently above the body as happens in this yoga. Even if it is done through the Sahasrara, well, the Sahasrara extends to the spiritualised mind and can be felt in the top of the head, so any ascent above is not indispensable. But, apart from that, one can very well, as you say, realise the Atman if one stands back from the mind and heart, detaches oneself from the parts of [p.272] Prakriti, ceases to identify oneself with mind, life and body, falls into an inner silence. One need not even explore the kingdoms of the inner mind or inner vital, still less is it compulsory to spread one's wings in ranges above. The Self is everywhere and by entering into full detachment and silence, or even by either detachment or silence, one can get anywhere some glimpse, some reflection, perhaps even a full reflection, or a sense of the Self's presence or of one's own immergence in that which is free, wide, silent, eternal, infinite. Obviously if it is a pure "I", of whatever nature, which gets the experience, it must be looked on by the consciousness that has the realisation as the individual self of the Being, Jivatman.
3. One can also have the experience of oneself as not the mind but the thinker, not the heart but the self or "I" which supports the feelings, not the life but that which supports life, not the body but that which assumes a body. This self can be obviously dynamic as well as silent; or else you may say that, even though still and immobile, from its silence it originates the dynamism of Nature. One can also feel this to be the Spirit one in all as well as the true "I" in oneself. All depends on the experience. Very usually, it is the experience of the Purusha, often felt first as the Witness silent, upholding all the nature; but the Purusha can also be experienced as the Knower and the Ishwara. Sometimes it is as or through the mental Purusha in one centre or another, sometimes as or through the vital Purusha that one can become aware of one's self or spirit. It is also possible to become aware of the secret psychic being within by itself as the true individual; or one can be aware of the psychic being as the pure "I" with these others standing in mind or vital as representatives in these domains or on these levels. According to one's experience one may speak of any of these as the Jiva or pure "I" (this last is a very dubious phrase) or the true Person or true Individual who knows himself as one with or a portion of or wholly dependent on the universal or transcendent Being and seeks to merge himself in that or ascend to that and be it or live in oneness with it. All these things are quite possible without any need of the overhead experience or of the stable overhead Permanence.
[p.273] 4. One may ask, first, why not then say that the Jivatman which can be realised in this way is the pure "I" of which the lower self has the experience and through which it gets its salvation ; and, secondly, what need is there of going into the overhead planes at all? Well, in the first place, this pure "I" does not seem to be absolutely necessary as an intermediary of the liberation whether into the impersonal Self or Brahman or into whatever is eternal. The Buddhists do not admit any soul or self or any experience of the pure "I"; they proceed by dissolving the consciousness into a bundle of Sanskaras, get rid of the Sanskaras and so are liberated into some Permanent which they refuse to describe or some Shunya. So the experience of a pure "I" or Jivatman is not binding on everyone who wants liberation into the Eternal but is content to get it without rising beyond the spiritualised mind into a higher Light above. I myself had my experience of Nirvana and silence in the Brahman, etc, long before there was any knowledge of the overhead spiritual planes; it came first simply by an absolute stillness and blotting out as it were of all mental, emotional and other inner activities-the body continued indeed to see, walk, speak and do its other business, but as an empty automatic machine and nothing more. I did not become aware of any pure "I" nor even of any self, impersonal or other, - there was only an awareness of That as the sole Reality, all else being quite unsubstantial, void, non-real. As to what realised that Reality, it was a nameless consciousness which was not other than That;1 one could perhaps say this, though hardly even so much as this, since there was no mental concept of it, but not more. Neither was I aware of any lower soul or outer self called by such and such a personal name that was performing this feat of arriving at the consciousness of Nirvana. Well, then what becomes of your pure "I" and lower "I" in all that? Consciousness (not this or that part of consciousness or an "I" of any kind) suddenly emptied itself of all inner contents and remained aware only of unreal surroundings and of Something real but ineffable. You may say that there must have been a consciousness aware of some perceiving existence, [p.274] if not of a pure "I", but, if so, it was something for which these names seem inadequate.
5. I have said the overhead ascension is not indispensable for the usual spiritual purposes, - but it is indispensable for the purposes of this yoga. For its aim is to become aware of and liberate and transform and unite all the being in the light of a Truth-consciousness which is above and cannot be reached if there is no entirely inward-going and no transcending and upward-going movement. Hence all the complexity of my psychological statements as a whole, not new in essence-for much of it occurs in the Upanishads and elsewhere, but new in its fullness of collective statement and its developments directed towards an integral yoga. It is not necessary for anyone to accept it unless he concurs in the aim; for other aims it is unnecessary and may very well be excessive.
6. But when one has made the inner exploration and the ascension, when one's consciousness is located above, one cannot be expected to see things precisely as they are seen from below. The Jivatman is for me the Unborn who presides over the individual being and its developments, associated with it but above it and them and who by the very nature of his existence knows himself as universal and transcendent no less than individual and feels the Divine to be his origin, the truth of his being, the master of his nature, the very stuff of his existence. He is plunged in the Divine and one with the Eternal for ever, aware of his own expression and instrumental dynamism which is the Divine's, dependent in love and delight, with adoration on That with which yet through that love and delight he is one, capable of relation in oneness, harmonic in this many-sidedness without contradiction, because this is another consciousness and existence than that of the mind, even of the spiritualised mind; it is an intrinsic consciousness of the Infinite, infinite not only in essence but in capacity, which can be to its own self-awareness all things and yet for ever the same and one. The triune realisation, therefore, full of difficulties for the mind, is quite natural, easy, indisputable to the supramental consciousness or, generally, to the consciousness of the upper hemisphere. It can be seen and felt as knowledge in all the spiritual planes, but the completely [p.275] indivisible knowledge, the full dynamics of it can only be realised through the supramental consciousness itself on its own plane or by its descent here.
7. The description of a pure "I" is quite insufficient to describe the realisation of the Jivatman - it is rather describable as the true Person or Divine Individual, though that too is not adequate. The word "I" always comes with an under-suggestion of ego, of separativeness; but there is no separativeness in this selfvision, for the individual here is a spiritual living centre of action for the One and feels no separation from all that is the One.
8. The Jivatman has its representative power in the individual nature here; this power is the Purusha upholding the Prakriti - centrally in the psychic, more instrumentally in the mind, vital and physical being and nature. It is therefore possible to regard these or any of them as if they were the Jiva here. All the same I am obliged to make a distinction not only for clear thinking but because of the necessity of experience and integral dynamic self-knowledge without which it is difficult to carry through this yoga. It is not indispensable to formulate mentally to oneself all this, one can have the experience and, if one sees clearly with an inner perception, it is sufficient for progress towards the goal. Nevertheless if the mind is clarified without falling into mental rigidity and error, things are easier for the sadhak of the yoga. But plasticity must be preserved, for loss of plasticity is the danger of a systematic intellectual formulation; one must look into the thing itself and not get tied up in the idea. Nothing of all this can be really grasped except by the actual spiritual experience.
Original note: 1 Mark that I did not think these things, there were no thoughts or concepts nor did they present themselves like that to any Me; it simply just was so or was self-apparently so.