What is the Truth? What do you mean when you speak of “the Truth”?

You want a mental definition of the Truth. The Truth cannot be expressed in mental terms. Yes, it is so. And all the questions put are mental questions.
The Truth cannot be formulated, it cannot be defined—it is to be lived.
And one who is wholly consecrated to the Truth, who wants to live the Truth, serve the Truth, will know at each moment what must be done: it will be a kind of intuition or revelation (most often without words, but sometimes also expressed in words) which will make you know at every minute what is the truth of thatminute. And it is this that is so interesting. You want to know “the Truth” as a thing well defined, well classified, well established, and after that you are at rest: there is no need to seek any more! You take it up, you say: “Here, this is the Truth” and then it is fixed. This is what all the religions have done. They have established their truth as a dogma. But it is not the Truth any more.
The Truth is something living, moving, expressing itself at each second, and it is one way of approaching the Supreme. Each one has his way of approaching the Supreme. There are perhaps some who are able to approach him from all sides at the same time, but there are those who approach through Love, those who approach through Power, those who approach through Consciousness and those who approach through Truth. But each of these aspects is as absolute, imperative and undefinable as the supreme Lord himself is. The supreme Lord is absolute, imperative and undefinable, unseizable in his action, and his attributes have this same quality.
Once one knows this, he who puts himself at the service of one of these aspects will know (it is expressed in life, in time, in the movement of time), will know at each moment what Truth is, and will know at each moment what Consciousness is, and will know at each minute what Power is, and he will know at each minute what Love is. And it is a multiform Power, Love, Consciousness, Truth that expresses itself innumerably in the manifestation, even as the Lord expresses himself innumerably in the manifestation.
[CWM2, 15:396-97]
If Truth is One and Universal, why there is so much quarrel and conflict among religions sects and ideologies on the nature of truth?
The dogmas of sects and the intolerance of religions come from the fact that the sects and religions consider their beliefs alone to be knowledge, and the beliefs of others to be error, ignorance or charlatanism.
This simple movement causes them to set up what they believe to be true as dogma and to violently condemn what others believe to be true. To think that your knowledge is the only true one, that your belief is the only true one and that others’ beliefs are not true, is to do precisely what is done by all sects and religions.
So, if you are doing exactly the same thing as the sects and religions, you have no right to mock them. You do the same thing without being aware of it because it seems quite natural to you. What Sri Aurobindo wants to make you understand is that when you say, “We are in possession of the truth and what is not this truth is an error”—though you may not dare say it in such a crude way—you are doing exactly the same thing as all the religions and all the sects.
If you objectify a little you will see that you have spontaneously, without realising it, established as knowledge everything you have learnt, everything you have thought, everything which has given you the impression of being particularly true and of major importance; and you are quite ready to contradict any different notion held by those who say, “No, no, it is like this, it is not like that.”
If you watch yourself in action, you will understand the mechanism of this intolerance and you will immediately be able to put an end to all these useless discussions. This brings us back to what I have already told you once: the contact which you have had with the truth of things, your personal contact—a contact which is more or less clear, profound, vast, pure—may have given you, as an individual, an interesting, perhaps even a decisive experience; but although this contact may have given you an experience of decisive importance, you must not imagine that it is a universal experience and that the same contact would give others the same experience. And if you understand this, that it is something purely personal, individual, subjective, that it is not at all an absolute and general law, then you can no longer despise the knowledge of others, nor seek to impose your own point of view and experience upon them. This understanding obviates all mental quarrels, which are always totally useless.
[CWM2, 10:20-21]
You see, thought is so approximate a thing, it is so far from the truth… it is only a kind of vague, incomplete, confused reflection, full of falsehood, even at its best. So, in truth, it is the moment to be practical and tell yourself, “Well, I shall adopt this thought if it helps me to progress.” But if you think that it is the absolute truth, you are sure to go wrong, for there is not a single thought which is the absolute truth.
Ah, yes, we are going to put into the books of the lending library of the University one of Sri Aurobindo’s short reflections, which is wonderful—I had it printed today—in which he says that any teaching, however great it may be, however pure, noble, true it may be, is only one aspect of the Truth and not the Truth itself (I am commenting, the text1 is not exactly this), it is not the entire Truth. Well, that is it. Whatever your thought may be, even if it is very high, very pure, very noble, very true, it is only a very tiny microscopic aspect of the Truth, and consequently it is not entirely true. So in that field one must be practical, as I said, adopt the thought for the time being, the one which will help you to make progress when you have it. Sometimes it comes as an illumination and this helps you to progress. So long as it helps you to make progress, keep it; when it begins to crumble, not to act any longer, well, drop it, and try to get another which will lead you a little farther.
Many miseries and misfortunes in the world would disappear if people knew the relativity of knowledge, the relativity of faith, the relativity of the teachings and also the relativity of circumstances… to what extent a thing is so relatively important! For the moment it may be capital, it may lead you to life or to death—I am not speaking of physical life and death, I am speaking of the life and death of the spirit—but this is for the moment; and when you have made a certain progress, when you have grown a few years older from the spiritual point of view, and you look back on this thing, this circumstance or idea which perhaps has decided your life, it will seem so relative, so insignificant to you… and you will need something much higher to make new progress.
If one could always remember this, well, one would avoid much sectarianism, much intolerance, and annul all quarrels immediately, because a quarrel means just this, that one thinks in one way and the other in another, that one has taken one attitude and the other another, and that instead of trying to bring them together and find out how they could be harmonised, one puts them over against each other as one fights with one’s fists. It is nothing else.
But if you become aware of the complete relativity of your point of view, your thought, your conviction of what is good, to what an extent it is relative in the march of the universe, then you will be less violent in your reactions and more tolerant. Here we are.
[CWM2, 6:358-59]
What is this truth of the being, and how is it expressed externally in physical life?
It is expressed in this way: each individual being has a direct and unique relation with the Supreme, the Origin, That which is beyond all creation. It is this unique relation which must be expressed in one’s life, through a unique mode of being in relation with the Divine. Therefore, each one is directly and exclusively in relation with the Divine—the relation one has with the Divine is unique and exclusive; so that you receive from the Divine, when you are in a receptive state, the totality of the relation it is possible for you to have, and this is neither a sharing nor a part nor a repetition, but exclusively and uniquely the relation which each one can have with the Divine. So, from the psychological point of view, one is all alone in having this direct relation with the Divine.
One is all alone with the Supreme.
The relation one has with Him will never have an equal, will never be exactly the same as another’s. No two are the same and therefore nothing can be taken away from you to be given to another, nothing can be withdrawn from you to be given to another. And if this relation disappeared from the creation, it would really disappear—which is impossible.
And this means that if one lives in the truth of one’s being, one is an indispensable part of the creation. Naturally, I don’t mean if one lives what one believes one should be, I am saying if one lives the truth of one’s being; if, by a development, one is able to enter into contact with the truth of one’s being, one is immediately in a unique and exclusive relation with the Divine, which hasn’t its equal.
There, now.
And naturally, because it is the truth of your being, that is what you should express in your life.
[CWM2, 8:279-80]
…that everyone belongs to a certain type, that, for example, the pine will never become the oak and the palm never become wheat. This is obvious. But that is something else: it means that the truth of your being is not the truth of your neighbour’s. But in the truth of your being, according to your own formation, your progress is almost unlimited. It is limited only by your own conviction that it is limited and by your ignorance of the true process, otherwise…
There is nothing one cannot do, if one knows how to do it.
[CWM2, 8:387]
If one finds the truth in things, does it mean that one has found the Divine?
Surely! In everything, whatever it is that is the only way. There is not a thing that does not carry in itself an eternal truth, otherwise it could not exist. The universe could not exist for even a thousandth part of a second if it did not contain a truth in itself.
[CWM2, 5:39]
You say that one should have “the certitude of Truth’s final victory”. But doesn’t this certitude seem very different from, and often the very opposite of, what one teaches in ordinary life?
Yes. Generally it is believed that things always end badly in Nature. Everyone knows the story of those who have met a lamentable end after having enjoyed great success in their life; of those who had extraordinary capacities and who finally lost them; of a nation which for a long period was the model of a marvellous civilisation—the civilisation vanishes and the nation is changed into something so deplorable that one can no longer recollect what it was. It seems that the story of the earth is a story of victories followed by defeats and not of defeats followed by victories.
But in fact, whenever it is a question of universal and divine things, what is needed is the universal vision and divine understanding of things in order to know how the truth expresses itself. There is a kind of general pessimism which says that even if things begin well they end badly, that it is weakness, hypocrisy, falsehood and wickedness which always seem to have the upper hand. That is why those who see the world in their own personal dimension have said that the world is bad and that we have only to finish with it and get out of it as soon as possible. Teachers have taught this but their teaching only proves that their vision is too narrow and in the dimension of their human individuality.
In truth, the movements of Nature are like those of the tides: they advance, they recede, advance and recede; in the universal life and even in terrestrial life, this means a progressive advance, though apparently it is cut up by withdrawals. But these withdrawals are only an appearance, as when one draws back to spring forward. You seem to be drawing back but it is simply in order to go much farther.
[CWM2, 4:22-23]