By concentration one reaches the knowledge within, which means one is able to see concretely and to be conscious of something which is apart from one's physical body. A person may be conscious of a poem, a word, a picture, an idea or something, and if he can be so conscious of it that he can lose the consciousness of his limited body for a moment, that is the first step. Although it seems very easy, it is not so easy. When a person begins to do it, no sooner does he dose his eyes in order to concentrate than a thousand things come before him. Also his physical body becomes restive. It says, 'This person is not conscious of me! ' And then he gets nervous and twists and turns in order to be conscious of the body. The body does not like a person to be unconscious of it. It is like a dog or a cat; it likes one to take notice of it. Then a kind of nervous action arises in the body. It feels like moving, turning, scratching, or something. As soon as one wants to discipline the body, the body does not want to accept discipline. The second stage is that instead of being conscious of a thought, one is conscious of a feeling, which is wider still; because thought is a form, and the mind even sees the form. But feeling has no form, therefore to fix one's mind on a feeling and to keep it with the intention of keeping it, is not an easy thing. If once a person has done it and has not given in to the restiveness of mind, then he certainly feels uplifted. This is the boundary of human progress and further than that is divine progress. What is divine progress? When one goes further still, then instead of being active one becomes passive. It is a state of consciousness, to be passive. There one does not need concentration, what one needs there is meditation. There one gets in touch with that power which is audible and visible within one and of which one is yet ignorant; that power which is busy moving towards the materialization of its intended object. Once one comes into contact with this experience, one can no longer say in later life that there is such a thing as an accident. Then one will see that all that happens is destined and prepared, when one catches it in its preparatory condition before it has manifested on the earthly plane. And if one goes further, there is consciousness in its aspect of pure intelligence. It is knowing and yet knowing nothing. And knowing nothing means knowing all things. Because it is the knowing of things that blunts the faculty of knowledge. In other words, when a person is looking in a mirror, his reflection covers the mirror and in that mirror nothing else can be reflected. Therefore when the consciousness is conscious of anything, it is blunted; at that moment it is blunted, or in other words it is covered by something that it is conscious of. The moment that cover is taken away, it is its own self, it is pure intelligence, it is pure spirit. In that condition its power, life, magnetism, force, its capacity, are much greater, incomparably greater than one can imagine. What it is cannot be explained except that by the help of meditation one reaches that condition. And if one goes higher still, it is not even consciousness, it is a kind of omniscient condition which is the sign of inner perfection. (from Hazrat Inayat Khan: Mental Purification)