Bhagavad-gita is the transcendental science of God spoken by the father of religion Himself, Lord Sri Krsna. It is the essence of all Vedic knowledge. By receiving Bhagavad-gita through the proper system, one can become cleansed of all sinful reactions and attain perfection in spiritual life.
Lord Krsna says in Bhagavad-gita:
imam vivasvate yoga
proktavan aham avyayam
vivasvan manave praha
manur iksvakave 'bravit
"I instructed this imperishable science of yoga to the sun-god, Vivasvan, and Vivasvan instructed it to Manu, the father of mankind, and Manu in turn instructed it to Iksvaku." (Bg. 4.1)
Srila Prabhupada, the author of Bhagavad-gita As It Is, says that the Gita was spoken to Vivasvan approximately 120,400,000 years ago and has been extant in human society for two million years. It was spoken again to Arjuna 5,000 years ago because in course of time the succession was broken and the science appeared to be lost. Detecting that the purpose of the Gita had been scattered by demoniac commentators, Krsna reestablished the disciplic succession 5,000 years ago by speaking theGita to Arjuna on the Battlefield of Kuruksetra. Arjuna's qualification for receiving Bhagavad-gita was that he was Krsna's devotee and friend (bhakto 'si me sakha ceti) .
His Divine Grace A.C. Bhaktivedanta Swami Prabhupada translated the Gita into English with authorized purports to convey its meaning straightforwardly because almost every commentary on Bhagavad-gita was the work of a self-motivated scholar, yogi or politician who did not accept Lord Sri Krsna as the Supreme Personality of Godhead. Such interpreters think that they can separate Krsna's body, soul and mind, for they do not know that Lord Krsna is absolute. He is sac-cid-ananda-vigraha: His body, soul and He Himself are one.
Krsna spoke Bhagavad-gita to Arjuna on the Battlefield of Kuruksetra just before Arjuna was to take part in a civil war. Krsna wanted Arjuna to fight, for it was his duty as a service to the Lord. But Arjuna did not want to kill his relatives and teachers who faced him on the battlefield. Arjuna, being thus confused, then accepted Lord Krsna as his spiritual master:
prcchami tvam dharma-sammudha-cetah
yac chreyah syan niscitam bruhi tan me
sisyas te 'ham sadhi mam tvam prapannam
"Now I am confused about my duty and have lost all composure because of weakness. In this condition I am asking You to tell me clearly what is best for me. Now I am Your disciple, and a soul surrendered unto You. Please instruct me." (Bg. 2.7)
Actually, we should all come to this stage of understanding that we are confused and that our best interest lies in accepting a bona fide spiritual master who is in the line of Sri Krsna so that we may solve the problems of life namely birth, death, old age and disease and go back home, back to Godhead. The problems of life appear without our wanting them. Is that not a fact? For example, no one wants to get old, become diseased or die, and if people fully understood the miseries of birth, they would be terrified of accepting rebirth. Yet these miseries are forced upon us. Krsna says in Bhagavad-gita, janma-mrtyu jara-vyadhi-duhkha-dosanudarsanam: one should be aware of the evils of birth (janma), death (mrtyu), old age (jara) and disease (vyadhi). The Vedic wisdom recommends that to become free from these fourfold miseries, one should approach a bona fide, Krsna conscious spiritual master in the line from Lord Sri Krsna Himself. Otherwise, if one fails to use his human intelligence to try to solve these problems, one is a miserly person (krpana) and meets his death just like cats and dogs.
Throughout Bhagavad-gita, and very elaborately in the Second Chapter, the Lord gives many examples to explain that one is not the body but an eternal spiritual soul who is a part and parcel of God. He says that the soul existed always, and always will exist. The soul is traveling from boyhood to youth, then to old age, and so, similarly, the soul passes into another body at death. The eternal (spirit) has no cessation, and the temporary (the body) has no endurance (nasato vidyate bhavo nabhavo vidyate satah). The soul can never be killed by anyone (vinasam avyayasyasya na kascit kartum arhati). The soul never takes birth and never dies (na jayate mriyate va kadacit). He is unborn (aja), eternal (nitya) and ever-existing (sasvat). He is undying and primeval. The soul is not slain when the body is slain (na hanyate hanyamane sarire).
In Bhagavad-gita, Lord Sri Krsna explains karma-yoga, jnana-yoga and mystic yoga system, but his final conclusive instructions are as follows:
man-mana bhava mad-bhakto
mad-yaji mam namaskuru
mam evaisyasi satyam te
pratijane priyo 'si me
mam ekam saranam vraja
aham tvam sarva-papebhyo
moksayisyami ma sucah
"Always think of Me and become My devotee. Worship Me and offer your homage unto Me. Thus you will come to Me without fail. I promise you this because you are My very dear friend. Abandon all varieties of religion and just surrender unto Me. I shall deliver you from all sinful reaction. Do not fear." (Bg. 18.65-66)
By surrendering unto the lotus feet of Krsna, we can become free from material bondage. Why, then, don't the philosophers, scientists, administrators and leaders of society surrender to Krsna? The Gita answers this quite frankly. Those who are actually learned leaders of society great figures in history like Brahma, Siva, Vyasa, Devala, Madhvacarya, Ramanujacarya, Sri Caitanya and many others surrender unto Lord Sri Krsna. But those who are only dressed like scientists, philosophers and leaders of society for material gain do not accept the plan and path of the Supreme Personality of Godhead.
Therefore, let us all worship Lord Krsna and be happy and go back to Godhead, for He is the cause of all causes (sarva-karana-karanam). He is the source of all spiritual and material worlds, and everything emanates from Him (aham sarvasya prabhavo mattah sarvam pravartate). He is the master and friend of every living entity.
To understand these ideas more fully, one may acquire a copy of Bhagavad-gita As It Is, with its translations and elaborate purports by His Divine Grace A.C. Bhaktivedanta Swami Prabhupada. His Divine Grace is an unalloyed devotee of Lord Sri Krsna who strictly follows the principles of disciplic succession through which Bhagavad-gita has been handed down over the centuries. Therefore he presents the spiritual knowledge of the Gita simply and clearly, without personally motivated interpretations. Please read Bhagavad-gita As It Is, with its true devotional purports by Srila Prabhupada. And chant Hare Krsna, Hare Krsna, Krsna Krsna, Hare Hare/ Hare Rama, Hare Rama, Rama Rama, Hare Hare. Your life will become sublime.