Vipassana meditation is a technique which aims at a state of consciousness in which you are aware of the body sensations (vedana), and in which you observe these sensations in a special way. This means observation without raga-dosa (likes-dislikes); as if you are standing on a balcony viewing the drama of these life processes, impartially observing the mind running here and there aimlessly like a monkey jumping from branch to branch.
Ordinarily, when we are conscious of anything, we see it with liking or disliking, love or hate, greed or jealousy or anger and so on. When this happens again and again, it leaves behind impressions (sankharas) in our mind. How many impressions are formed each day? We do not know, as we are unconscious of them. The number of impressions in one life seems infinite. If past lives are also accounted for, the impressions will be countless. However we cannot comprehend this, as the conscious mind is limited and the unconscious is beyond our awareness.
When we are operating at the superficial conscious level, there are sometimes bursts of anger, violence, laughing or crying spells on an individual or a mass scale; the so-called mad behaviour. Some moments later we may feel ashamed and guilty for such behaviour and we are unable to account for it. Actually, when one is "out of one's mind," it means that some of the infinite impressions from the unconscious mind have surfaced and burst before one can notice them, and therefore one gets overpowered.
Unconsciously, some of these impressions are surfacing all the time on our body and producing various sensations. But our conscious mind, as it is occupied with so many things, does not notice them. If our mind is concentrated, alert and silent, we become aware of these body sensations, some pleasant, some unpleasant. If we continue to watch these without liking or disliking, scanning the body, from the head to the feet, and from the feet up to the head, more and more impressions will surface, producing various sensations on different parts of the body.
If this practice is followed diligently, sincerely and regularly, the time will come when these impressions, though seemingly infinite, will go on surfacing on the body and will get exhausted. Then there will be nothing unconscious, only pure consciousness; no parts, but wholeness. This is Vipassana meditation. Even before this state is reached, by practising this technique, the mind is concentrated (not roaming in all directions like a monkey), is alert (not sleepy or dreaming), is quiet and silent (no agitation or disturbances) and is at peace for long intervals; the peace that passeth understanding.
Ordinarily there is temporary peace when one desire is fulfilled; this lasts till it is disturbed by another desire surfacing. We attribute this short temporary peace to our obtaining that particular desired object. So we ceaselessly struggle to satisfy all sorts of desires to get these short glimpses of peace or happiness. Our whole life is nothing but a pursuit, a struggle, for this temporary happiness, and for much of the time there is no peace or happiness but unhappiness, frustration and misery. But during Vipassana meditation, it is not so; the mind is equanimous, free from craving and aversion, all the while observing these body sensations, however pleasant or unpleasant they may be. It is not disturbed, is silent and peaceful, and stays happy for a longer and longer duration.
As one gets more and more established in the practice of meditation, there are fewer mental problems, and even psychosomatic disorders like hypertension, peptic ulcer, irritable bowel syndrome, asthma and eczema get ameliorated. Vipassana meditation, therefore, leads to better health and a happy, blissful mind. There is less mental tension and confusion, and with such a clear and calm mind, one is able to deal easily with one's problems, thus living a merry and joyful life.