It has only 18 Hymns or Stanzas. Mahatma Gandhi said that if all the Scriptures of Hinduism were destroyed, with the exception of first 3 stanzas of this Upanishad, Hindu Dharma would not suffer total extinction. The mantras of this Upanishad can be grouped in to several parts. First 3 mantras mention 5 duties, the performance of which alone can lead to acquisition of Brahama-Vidya. These are :
1. Belief that God exists everywhere and has created everything in this universe. “Jagat” means which moves. Every thing in this universe is in motion. It is in motion, not by itself. Deep faith in God is necessary. One is to believe that God is all pervading and is present everywhere and that He is not stationed at one place. He does not move, but still present everywhere, because he is already present in each and everything is this universe. A person always seeks a lonely place for committing sin or crime. If it is believed that God is present everywhere, then there will be no place where we are not being watched.
2. The Upanishad enjoins that man should enjoy things, which are given to him by God. All things belong to him and we only have a right to use them, enjoy them. We should not get attached to them. Thieves, dacoits and rulers snatch away things from the people. There is however, a greater power that snatches away every thing from people and that power is called Death. The reason death is painful is because of our attachment. When a person sees death through the mirror of attachments it becomes awful and fearful. One could argue that if there is no attachment to things, we can’t give our best in accomplishing things in life. Our sages tell us that it is possible to protect things, which are given to a person for use and also enjoy them as well without attachment.
3. The third duty is that no one should covet the wealth, property or possession of others. If wealth of others is not taken away, If the sovereignty of others is not snatched or jeopardized, if there is no interference in the independence of others, discontentment will not arise.
4. The fourth duty is that one should aspire to live for a hundered years, doing deeds which do not cling to oneself. There is no other way except that of Karma-yoga. Everything in this universe is in constant motion. The Upanishads direct us that man should work, up to the last moment of his life. Renunciation of acts is no doubt called Sanyas. But it should be remembered that only those acts "that" are motivated (done with an eye on fruits) are to be renounced. Unmotivated (Nishkam karma-done as a duty with no desire for fruits or rewards) should never be given up.
5. The Upanishad says that persons who act against the dictates of their conscience, go after death, in to lower incarnations, which are enveloped in darkness. Manu ji has said that “Dharma” are acts, which are approved by one’s own conscience. Good conduct is the habit of doing good deeds, not out of person’s own volition but by forces of habit.
Performance of above duties is first step towards acquisition of knowledge of soul. According to Vedas there are three independent distinct eternal entities in this universe. God, soul and nature. God is Sat, chit and Anand or bliss. Soul is Sat and Chit (conscious), whereas the nature is only Sat or true and not mithya or unreal.
Mantras 4 to 8 contain the roots of important principles of Braham-Vidya.
The fourth and fifth mantras say that the God does not move from place to place, is unshakable, faster than even the mind, and all pervading. Also because of his omnipotence and all pervading nature, transgresses our mind and other senses. All beings exist and live in him doing good or bad deeds. God cannot be perceived/seen by our eyes or other senses can only be experienced by soul once it is disconnected from external sensory input, as in the state of deep meditation. (Dhyana-fixation or concentration of power at one point, Dharna-concentration of power in the soul, Samadhi-highest state of Dharna.).
The sixth mantra means that one who after careful consideration, sees all beings and things as existing in the supreme soul and also sees him as existing in all beings and things, cannot do bad deeds or be bad to any one. There comes the concept of love for all.
The seventh mantra explains that “he who after careful consideration, knows and sees all beings, like himself, as existing in the all pervading God, becomes Stith Pragya, and does not suffer from pain due to any loss or feel over joyed from achievements or gains.
The eighth mantra is really the most perfect definition of God. God is omnipresent, pure, formless, without holes, free from any body organs, sinless, knower of everything including our minds, all pervading, self-existent (unborn i.e., never takes birth or dies), has created and runs this universe and has given us the knowledge “Vedas” exactly as needed in a perfect way since eternity on an ongoing basis. One who does “Jap” should repeatedly think in his/her mind about various qualities/attributes of God. People who perform Sandhya should aspire for physical, mental and spiritual progress. Constant pondering over the qualities of God results in the illumination of the mind and generation of universal love. When the Yogi finds God in every inanimate and animate thing in this world he becomes free from grief and attachment. In state of meditation Yogi sees none other than God. When he has lost his ego in the love of God how can the material objects of the world disturb his peace of mind or grief and attachments affect him.
The ninth, tenth and eleventh Mantras emphasize that both materialism and spiritualism are necessary to make life useful and complete. Those who are engrossed only in materialism or rituals fall in to blind darkness, while those who are engrossed in acquiring knowledge only fall in to even greater darkness. Knowledge and acts(karma) should go together. Materialistic knowledge and progress help improve the quality of life and may prolong life as well. Spiritual knowledge and conduct according to Vedic guidance will help attain salvation by attaining purity of mind and soul and realization of God. It is stated in these mantras that actions are superior to knowledge, because mere knowledge does not bear any fruit, whereas an act, good or bad, bears its fruits without fail. Accordingly, in the philosophy of the Upanishad acts have a higher place than knowledge and no student of spiritual knowledge should loose sight of this.
The 12-14th Mantras discuss the importance of worshiping both the “manifest and unmanifested Prakriti”. These also deal with individualism (asambhutim) and socialism (sambhutim). By personal care, one can take care of oneself in the matters of physical needs such as food, shelter, and health care only, but it increases selfishness. On the other hand being engrossed in social service only can make one ignore personal needs. So both are necessary.
Basically these mantras also deal with the concept of three bodies-physical, subtle (which comprises of five senses: touch, smell, taste, sight and hearing, five elements: water, air, fore, earth and ether, five pranas: pran, apan, vyan, saman, and udan, mind and intellect) and causal. Also deals with five koshas Annamaya(food), Pranmaya(air sheath), mannomay(mental), vigyanmy(intellectual) and Anandmaya(bliss). In the waking state, there is connection of three bodies with each other. In dream state, there in disconnection of physical and subtle body, but the causal body remains connected to the subtle body. In sleep state, all three bodies are disconnected form each other. When this happens in the awake state, this is what is to be achieved in the state of dharna, dhyana and samadhi.
Worship of God consists in experiencing in one’s mind His divine attributes and qualities. His attributes are that he is soundless, touchless, formless, imperishable, eternal, endless, beginingless etc. He is all pervading, luminous, pure, wise, omniscient, transcendent, self-existing etc.
The fifteenth mantra “Hiranmayan patren—“ deals with the request to God to please remove the golden lid and uncover the truth in life. Wealth entices away man from the path of truth(duty). Dharma is life of truth and justice. God(brahm) is truth. In order to attain God one should follow truth.
In sixteenth mantra the concept is that god is pushan (nourisher of everyone), Yam (justice giver), luminous and dispeller of darkness and protector of all.
Also that many times we get so absorbed in nature that we forget the real one, the creator. Similarly we get so engrossed in the physical aspects of body that we forget the soul within, which is really the real self, and also forget about the god inside our soul, the Sat, Chit and Anand God.
17th Mantra deals with mortality of body and immortality of soul. Upanishad instructs us that when time comes for the soul to quit the mortal body one should recite Om. There is a built in concept here, that although there are laws laid down by God, the person(being) has full liberty to do acts during lifetime. There are instructions to remember god in all our future actions. It is believed that during the last moments of our life we don’t have the freedom to act, as we want. A picture or film of our life long past actions appears before our eyes, and we depart from this world fully conscious of our good and evil deeds.
The last mantra is a prayer to god to lead us through a righteous path, and to save us from the path of sin. Also there is Namaste to God. God is our ultimate and most ancient guru. Surrender to God is the path to salvation.