This warning against the dangers of the intermediate zone was given by Sri Aurobindo in a long letter which was first published in 1933 in the book 'The Riddle of this World'. You can read it now in 'Letters on Yoga', Part 3, Section 3 'Experiences of the Inner and the Cosmic Consciousness', Subsection 5, pages 1039-1046.
All these experiences are of the same nature and what applies to one applies to another. Apart from some experiences of a personal character, the rest are either idea-truths, such as pour down into the consciousness from above when one gets into touch with certain planes of being, or strong formations from the larger mental and vital worlds which, when one is directly open to these worlds, rush in and want to use the sadhak for their fulfilment.
These things, when they pour down or come in, present themselves with a great force, a vivid sense of inspiration or illumination, much sensation of light and joy, an impression of widening and power. The sadhak feels himself freed from the normal limits, projected into a wonderful new world of experience, filled and enlarged and exalted;what comes associates itself, besides, with his aspirations, ambitions, notions of spiritual fulfilment and yogic siddhi; it is represented even as itself that realisation and fulfilment. Very easily he is carried away by the splendour and the rush, and thinks that he has realised more than he has truly done, something final or at least something sovereignly true. At this stage the necessary knowledge and experience are usually lacking which would tell him that this is only a very uncertain and mixed beginning; he may not realise at once that he is still in the cosmic Ignorance, not in the cosmic Truth, much less in the Transcendental Truth, and that whatever formative or dynamic idea-truths may have come down into him are partial only and yet further diminished by their presentation to him by a still mixed consciousness. He may fail to realise also that if he rushes to apply what he is realising or receiving as if it were something definitive, he may either fall into confusion and error or else get shut up in some partial formation in which there may be an element of spiritual Truth but it is likely to be outweighted by more dubious mental and vital accretions that deform it altogether.
It is only when he is able to draw back (whether at once or after a time) from his experiences, stand above them with the dispassionate witness consciousness, observe their real nature, limitations, composition, mixture that he can proceed on his way towards a real freedom and a higher, larger and truer siddhi. At each step this has to be done. For whatever comes in this way to the sadhak of this yoga, whether it be from overmind or Intuition or Illumined Mind or some exalted Life Plane or from all these together, it is not definitive and final; it is not the supreme Truth in which he can rest, but only a stage. And yet these stages have to be passed through, for the supramental or the Supreme Truth cannot be reached in one bound or even in many bounds; one has to pursue a calm patient steady progress through many intervening stages without getting bound or attached to their lesser Truth or Light or Power or Ananda.
This is in fact an intermediary state, a zone of transition between the ordinary consciousness in mind and the true yoga knowledge. One may cross without hurt through it, perceiving at once or at an early stage its real nature and refusing to be detained by its half-lights and tempting but imperfect and often mixed and misleading experiences; one may go astray in it, follow false voices and mendacious guidance, and that ends in a spiritual disaster; or one may take up one's abode in this intermediate zone, care to go no farther and build there some half-truth which one takes for the whole truth or become the instrument of the powers of these transitional planes, - that is what happens to many sadhaks and yogis.
Overwhelmed by the first rush and sense of power of a supernormal condition, they get dazzled with a little light which seems to them a tremendous illumination or a touch of force which they mistake for the full Divine Force or at least a very great yoga Shakti; or they accept some intermediate Power (not always a Power of the Divine) as the Supreme and an intermediate consciousness as the supreme realisation. Very readily they come to think that they are in the full cosmic consciousness when it is only some front or small part of it or some larger Mind, Life-Power or subtle physical ranges with which they have entered into dynamic connection. Or they feel themselves to be in an entirely illumined consciousness, while in reality they are receiving imperfectly things from above through a partial illumination of some mental or vital plane; for what comes is diminished and often deformed in the course of transmission through these planes; the receiving mind and vital of the sadhak also often understands or transcribes ill what has been received or throws up to mix with it its own ideas, feelings, desires, which it yet takes to be not its own but part of the Truth it is receiving because they are mixed with it, imitate its form, are lit up by its illumination and get from this association and borrowed light an exaggerated value.
There are worse dangers in this intermediate zone of experience. For the planes to which the sadhak has now opened his consciousness, - not as before getting glimpses of them and some influences, but directly, receiving their full impact, - send a host of ideas, impulses, suggestions, formations of all kinds, often the most opposite to each other, inconsistent or incompatible, but presented in such a way as to slur over their insufficiencies and differences, with great force, plausibility and wealth of argument or a convincing sense of certitude. Overpowered by this sense of certitude, vividness, appearance of profusion and richness, the mind of the sadhak enters into a great confusion which it takes for some larger organisation and order; or else it whirls about in incessant shiftings and changes which it takes for a rapid progress but which lead nowhere. Or there is the opposite danger that he may become the instrument of some apparently brilliant but ignorant formation; for these intermediate planes are full of little Gods or strong Daityas or smaller beings who want to create, to materialise something or to enforce a mental and vital formation in the earth life and are eager to use or influence or even possess the thought and will of the sadhak and make him their instrument for the purpose. This is quite apart from the well-known danger of actually hostile beings whose sole purpose is to create confusion, falsehood, corruption of the sadhana and disastrous unspiritual error. Anyone allowing himself to be taken hold of by one of these beings, who often take a divine Name, will lose his way in the yoga. On the other hand, it is quite possible that the sadhak may be met at his entrance into this zone by a Power of the Divine which helps and leads him till he is ready for greater things; but still that itself is no surety against the errors and stumblings of this zone; for nothing is easier than for the powers of these zones or hostile powers to imitate the guiding Voice or Image and deceive and mislead the sadhak or for himself to attribute the creations and formations of his own mind, vital or ego to the Divine.
For this intermediate zone is a region of half-truths - and that by itself would not matter, for there is no complete truth below the supermind; but the half-truth here is often so partial or else ambiguous in its application that it leaves a wide field for confusion, delusion and error. The sadhak thinks that he is no longer in the old small consciousness at all, because he feels in contact with something larger or more powerful, and yet the old consciousness is still there, not really abolished. He feels the control or influence of some Power, Being or Force greater than himself, aspires to be its instrument and thinks he has got rid of ego; but this delusion of egolessness often covers an exaggerated ego. Ideas seize upon him and drive his mind which are only partially true and by over-confident misapplication are turned into falsehoods; this vitiates the movements of the consciousness and opens the door to delusion. Suggestions are made, sometimes of a romantic character, which flatter the importance of the sadhak or are agreeable to his wishes and he accepts them without examination or discriminating control. Even what is true, is so exalted or extended beyond its true pitch and limit and measure that it becomes the parent of error. This is a zone which many sadhaks have to cross, in which many wander for a long time and out of which a great many never emerge.
Especially if their sadhana is mainly in the mental and vital, they have to meet here many difficulties and much danger; only those who follow scrupulously a strict guidance or have the psychic being prominent in their nature pass easily as if on a sure and clearly marked road across this intermediate region. A central sincerity, a fundamental humility also save from much danger and trouble. One can then pass quickly beyond into a clearer Light where if there is still much mixture, incertitude and struggle, yet the orientation is towards the cosmic Truth and not to a half-illumined prolongation of Maya and ignorance.
I have described in general terms with its main features and possibilities this state of consciousness just across the border of the normal consciousness, because it is here that these experiences seem to move. But different sadhaks comport themselves differently in it and respond sometimes to one class of possibilities, sometimes to another. In this case it seems to have been entered through an attempt to call down or force a way into the cosmic consciousness - it does not matter which way it is put or whether one is quite aware of what one is doing or aware of it in these terms, it comes to that in substance. It is not the overmind which was entered, for to go straight into the overmind is impossible. The overmind is indeed above and behind the whole action of the cosmic consciousness, but one can at first have only an indirect connection with it; things come down from it through intermediate ranges into a larger mind-plane, life-plane, subtle physical plane and come very much changed and diminished in the transmission, without anything like the full power and truth they have in the overmind itself on its native levels. Most of the movements come not from the overmind, but down from higher mind ranges. The ideas with which these experiences are penetrated and on which they seem to rest their claim to truth are not of the overmind, but of the higher Mind or sometimes of the illumined Mind; but they are mixed with suggestions from the lower mind and vital regions and badly diminished in their application or misapplied in many places. All this would not matter; it is usual and normal, and one has to pass through it and come into a clearer atmosphere where things are better organised and placed on a surer basis. But the movement was made in a spirit of excessive hurry and eagerness, of exaggerated self-esteem and self-confidence, of a premature certitude, relying on no other guidance than that of one's own mind or of the ''Divine'' as conceived or experienced in a stage of very limited knowledge. But the sadhak's conception and experience of the Divine, even if it is fundamentally genuine, is never in such a stage complete and pure; it is mixed with all sorts of mental and vital ascriptions and all sorts of things are associated with this Divine guidance and believed to be part of it which come from quite other sources. Even supposing there is any direct guidance, - most often in these conditions the Divine acts mostly from behind the veil, - it is only occasional and the rest is done through a play of forces; error and stumbling and mixture of Ignorance take place freely and these things are allowed because the sadhak has to be tested by the world-forces, to learn by experience, to grow through imperfection towards perfection - if he is capable of it, if he is willing to learn, to open his eyes to his own mistakes and errors, to learn and profit by them so as to grow towards a purer Truth, Light and Knowledge.
The result of this state of mind is that one begins to affirm everything that comes in this mixed and dubious region as if it were all the Truth and the sheer Divine Will; the ideas or the suggestions that constantly repeat themselves are expressed with a self-assertive absoluteness as if they were Truth entire and undeniable. There is an impression that one has become impersonal and free from ego, while the whole tone of the mind, its utterance and spirit are full of vehement self-assertiveness justified by the affirmation that one is thinking and acting as an instrument and under the inspiration of the Divine. Ideas are put forward very aggressively that can be valid to the mind, but are not spiritually valid; yet they are stated as if they were spiritual absolutes. For instance, equality, which in that sense - for yogic Samata is a quite different thing - is a mere mental principle, the claim to a sacred independence, the refusal to accept anyone as Guru or the opposition made between the Divine and the human Divine etc., etc. All these ideas are positions that can be taken by the mind and the vital and turned into principles which they try to enforce on the religious or even the spiritual life, but they are not and cannot be spiritual in their nature. There also begin to come in suggestions from the vital planes, a pullulation of imaginations romantic, fanciful or ingenious, hidden interpretations, pseudo-intuitions, would-be initiations into things beyond, which excite or bemuse the mind and are often so turned as to flatter and magnify ego and self-importance, but are not founded on any well-ascertained spiritual or occult realities of a true order. This region is full of elements of this kind and, if allowed, they begin to crowd on the sadhak; but if he seriously means to reach the Highest, he must simply observe them and pass on. It is not that there is never any truth in such things, but for one that is true there are nine imitative falsehoods presented and only a trained occultist with the infallible tact born of long experience can guide himself without stumbling or being caught through the maze. It is possible for the whole attitude and action and utterance to be so surcharged with the errors of this intermediate zone that to go farther on this route would be to travel far away from the Divine and from the yoga.
Here the choice is still open whether to follow the very mixed guidance one gets in the midst of these experiences or to accept the true guidance. Each man who enters the realms of yogic experience is free to follow his own way; but this yoga is not a path for anyone to follow, but only for those who accept to seek the aim, pursue the way pointed out upon which a sure guidance is indispensable. It is idle for anyone to expect that he can follow this road far, - much less go to the end by his own inner strength and knowledge without the true aid or influence. Even the ordinary long-practised yogas are hard to follow without the aid of the Guru; in this which as it advances goes through untrodden countries and unknown entangled regions, it is quite impossible. As for the work to be done it also is not a work for any sadhak of any path; it is not, either, the work of the ''Impersonal'' Divine who, for that matter, is not an active Power but supports impartially all work in the universe. It is a training ground for those who have to pass through the difficult and complex way of this yoga and none other. All work here must be done in a spirit of acceptance, discipline and surrender, not with personal demands and conditions, but with a vigilant conscious submission to control and guidance. Work done in any other spirit results in an unspiritual disorder, confusion and disturbance of the atmosphere. In it too difficulties, errors, stumblings are frequent, because in this yoga people have to be led patiently and with some field for their own effort, by experience, out of the ignorance natural to Mind and Life to a wider spirit and a luminous knowledge. But the danger of an unguided wandering in the regions across the border is that the very basis of the yoga may be contradicted and the conditions under which alone the work can be done may be lost altogether. The transition through this intermediate zone - not obligatory, for many pass by a narrower but surer way - is a crucial passage; what comes out of it is likely to be a very wide or rich creation; but when one founders there, recovery is difficult, painful, assured only after a long struggle and endeavour.