The famous sage, Ramana Maharshi, defined the whole of Vedanta in one sentence which he oft used to repeat, "Deham Naham Kohum Soham”. This is the essence of Vedanta. If you know this, not theoretically but experientially, you have known all the Upanishads and Vedanta. According to Raman Maharshi, if anybody goes deeper into the matter and asks, “If I am not the body then Who am I?”, the answer is “Soham”. He said that when one asks this question, Koham? Soham is the answer. I am not different from that Supreme Being.
The study of the Upanishads is not for weak minds because one has to take a totally different view of the world. It requires a great deal of mental strength to understand the Upanishad in theory and even more to live it. It is not a philosophy of running away from anything but living where you are and understanding the permanence of the Inner Reality. Those who believe in the permanence of this world wander around in darkness.
The Isavasya Upanishad describes this Supreme Truth, that we seek, as that which does not move and yet it is swifter than the mind and the senses. This seems to be one of the Upanishadic contradictions. It is a typical attempt to describe the undescribable, which is what the Upanishads are all about. It is unmoving unlike the nature of the mind which is always in movement.
Even the search for something or the attempt to achieve something is movement.
The Supreme Reality, the Atman or Isha pervades everything there is. If something is everywhere, there is no question of moving from here to there to find it. As this Reality that we seek is everywhere, the mind cannot move to it fast enough because it is there already.
The Upanishads say that this Reality is also beyond the reach of the senses. Attaining knowledge of this Supreme Reality is not an activity of the senses. Since the senses cannot reach it, the stress is on meditation alone: on going within oneself.
Perhaps one can find this Truth, this permanent bliss, when all movement ceases. When the mind finally understands that no amount of achieving and accumulating will bring lasting happiness, when all grasping and searching stops, when the mind becomes still and quiet. In that utter stillness, the Truth finally comes into being.