How do we know?
Knowledge from within
Nothing can be taught to the mind which is not already concealed as potential knowledge in the unfolding soul of the creature. So also all perfection of which the outer man is capable, is only a realising of the eternal perfection of the Spirit within him. We know the Divine and become the Divine, because we are That already in our secret nature. All teaching is a revealing, all becoming is an unfolding. Self-attainment is the secret; self-knowledge and an increasing consciousness are the means and the process.
—Sri Aurobindo, The Synthesis of Yoga, p. 54
Ancient Indian thought meant by knowledge a consciousness which possesses the highest Truth in a direct perception and in self-experience; to become, to be the Highest that we know is the sign that we really have the knowledge.
—Sri Aurobindo, The Life Divine, p. 712
For the inner knowledge comes from within and above (whether from the Divine in the heart or from the Self above) and for it to come, the pride of the mind and vital in the surface mental ideas and their insistence on them must go. One must know that one is ignorant before one can begin to know.
—Sri Aurobindo, Letters on Yoga, Part-3, p. 350
The true sense of the guidance becomes clearer when we can go deep within and see from there more intimately the play of the forces and receive intimations of the Will behind them. The surface mind can get only an imperfect glimpse. When we are in contact with the Divine or in contact with an inner knowledge and vision, we begin to see all the circumstances of our life in a new light and can observe how they all tended, without our knowing it, towards the growth of our being and consciousness, towards the work we had to do, towards some development that had to be made, -- not only what seemed good, fortunate or successful but also the struggles, failures, difficulties, upheavals. But with each person the guidance works differently according to his nature, the conditions of his life, his cast of consciousness, his stage of development, his need of further experience. We are not automata but conscious beings and our mentality, our will and its decisions, our attitude to life and demand on it, our motives and movements help to determine our course: they may lead to much suffering and evil, but through it all, the guidance makes use of them for our growth in experience and consequently the development of our being and consciousness. All advance, by however devious ways, even in spite of what seems a going backwards or going astray, gathering whatever experience is necessary for the soul's destiny. When we are in close contact with the Divine, a protection can come which helps or directly guides or moves us: it does not throw aside all difficulties, sufferings or dangers, but it carries us through them and out of them — except where for a special purpose there is need of the opposite.
—Sri Aurobindo, Letters on Yoga, Part-2, p. 177
Knowledge by identity
If we go deep enough into mental human knowledge, we realise that all this knowledge as we have it externally in the mental consciousness is scarcely anything more than a language--a fairly complicated one--making it possible for us to understand each other but corresponding only very remotely to the truth of things.
There is a direct approach by identity which is much more effective and, so to say, gives you the concrete key to the whole machinery of things, a direct key that needs no complicated science to express itself--something that corresponds to movements of consciousness and will, which would not need all the mental complications to express themselves. Then the universal reality in its totality becomes a symbol and can be directly perceived in its essence.
—The Mother, MCW, Vol. 9, p. 285
Two preparatory movements
We read, we try to understand, we explain, we try to know. But a single minute of true experience teaches us more than millions of words and hundreds of explanations.
So the first question is: "How to have the experience?"
To go within yourself, that is the first step.
And then, once you have succeeded in going within yourself deeply enough to feel the reality of that which is within, to widen yourself progressively, systematically, to become as vast as the universe and lose the sense of limitation.
These are the first two preparatory movements.
And these two things must be done in the greatest possible calm, peace and tranquillity. This peace, this tranquillity brings about silence in the mind and stillness in the vital.
This effort, this attempt must be renewed very regularly, persistently. And after a certain lapse of time, which may be longer or shorter, you begin to perceive a reality that is different from the reality perceived in the ordinary, external consciousness.
Naturally, by the action of Grace, the veil may suddenly be rent from within, and at once you can enter the true truth; but even when that happens, in order to obtain the full value and full effect of the experience, you must maintain yourself in a state of inner receptivity, and to do that, it is indispensable for you to go within each day.
—The Mother, MCW, Vol. 10, pp. 19-20
Faith: foreknowledge of the soul
... Faith does not depend upon experience; it is something that is there before experience. When one starts the yoga, it is not usually on the strength of experience, but on the strength of faith. It is so not only in yoga and the spiritual life, but in ordinary life also. All men of action, discoverers, inventors, creators of knowledge proceed by faith and, until the proof is made or the thing done, they go on in spite of disappointment, failure, disproof, denial because of something in them that tells them that this is the truth, the thing that must be followed and done. Ramakrishna even went so far as to say, when asked whether blind faith was not wrong, that blind faith was the only kind to have, for faith is either blind or it is not faith but something else —reasoned inference, proved conviction or ascertained knowledge.
Faith is the soul's witness to something not yet manifested, achieved or realised, but which yet the Knower within us, even in the absence of all indications, feels to be true or supremely worth following or achieving. This thing within us can last even when there is no fixed belief in the mind, even when the vital struggles and revolts and refuses. Who is there that practises the yoga and has not his periods, long periods of disappointment and failure and disbelief and darkness? But there is something that sustains him and even goes on in spite of himself, because it feels that what it followed after was yet true and it more than feels, it knows. The fundamental faith in yoga is this, inherent in the soul, that the Divine exists and the Divine is the one thing to be followed after —nothing else in life is worth having in comparison with that. So long as a man has that faith, he is marked for the spiritual life and I will say that, even if his nature is full of obstacles and crammed with denials and difficulties, and even if he has many years of struggle, he is marked out for success in the spiritual life.
— Sri Aurobindo, Letters on Yoga, Part-2, pp. 92-93
[F]or the knowledge of the Self it is necessary to have the power of a complete intellectual passivity, the power of dismissing all thought, the power of the mind to think not at all which the Gita in one passage enjoins. This is a hard saying for the occidental mind to which thought is the highest thing and which will be apt to mistake the power of the mind not to think, its complete silence for the incapacity of thought. But this power of silence is a capacity and not an incapacity, a power and not a weakness. It is a profound and pregnant stillness. Only when the mind is thus entirely still, like clear, motionless and level water, in a perfect purity and peace of the whole being and the soul transcends thought, can the Self which exceeds and originates all activities and becomings, the Silence from which all words are born, the Absolute of which all relativities are partial reflections manifest itself in the pure essence of our being. In a complete silence only is the Silence heard; in a pure peace only is its Being revealed. Therefore to us the name of That is the Silence and the Peace.
— Sri Aurobindo, The Synthesis of Yoga, p. 316