These eighteen verses can be divided into four parts.
The first part consists of the first three verses; the second part consists of the next four verses; the third part consists of the next seven verses; and the fourth part consists of the last four verses.
The first part deals with the science and art of life which is appropriate for every individual because we all need to know what life is and the art of living. These three verses tell us that life consists of concentric circles of movement – jagaty?m jagat, every little portion of life that we may touch, is a kind of circle and that circle is part of a bigger circle and that bigger circle is a part of a greater circle and so on, unending. All these concentric movements are inhabited by the Lord. There is a Lord of Existence, about whom a constant question is raised, – "Does God exist?" This is the supreme question which has been asked throughout history. This Upanishad declares that not only does God exist, but he inhabits every part of this universe. He is Isha. He is master of the universe. Therefore, everything belongs to Him. This is the basic premise and the art of life flows from it. While living in the world, we must not covet what belongs to another. The Isha Upanishad says that since everything belongs to God and God is present in everything, even if we try to possess something for ourselves, we will not succeed. We can only enjoy everything that exists around us and in the world. We should not deny ourselves anything, on one condition, ― we must admit that all this belongs to the Lord and we must renounce all this to the Lord. The moment we renounce it to the Lord, this very act of renunciation will give us the capacity to enjoy everything.
The first verse states:
īśāvāsyam idam sarvam yat kiñca jagatyām jagat
tena tyaktena bhuñjīthā mā grdhah kasya svid dhanam –1
All this is for habitation by the Lord, whatsoever is individual universe of movement in the universal motion. (Concentric motion is part of a larger universal motion) By that renounced thou shouldst enjoy; lust not after any man's possession.
Psychologically a difficulty arises whenever we want to renounce or give up something; we tend to become inactive. Acquisition, possession, enjoyment, relationship are our normal tendencies of action. The moment we are told that we have to renounce, we tend to remain inactive. A wrong idea has arisen in many cultures including India that renunciation is the best thing to do. Give up responsibilities, come out of this mess of life, and be inactive. Attain to a state where you don't need to do anything at all or do the most minimal things just to preserve the body.
To prevent this misunderstanding, this Upanishad tells us renunciation does not mean that we should give up works. On the contrary, by doing works in this world itself, we should wish to live for a hundred years. This is the only path, if we give up the path of action then there is great difficulty. And it adds that when we act, we should not be afraid that we will get stuck to possession. There is an art of acting by which even if we act, we will not become attached to possession, and we will not be stuck to any kind of limitation. Normally, our actions create reactions and lead us to further action and only in that kind of a circle we go on acting and reacting. But there is an art of life, which arises out of renunciation as a result of which, even if we act, we remain free