The Bhagavad-gita (Song of the Supreme Soul) is one of the most authoritative yoga scriptures. To actually understand the message of Bhagavad-gita, Krishna (the speaker of Bhagavad-gita) advises that one must be both a devotee and friend of the Lord:
"That very ancient science of the relationship with the Supreme is today told by Me to you because you are My devotee as well as My friend and can therefore understand the transcendental mystery of this science."Bhagavad-gita 4.3
The conversation between Krishna and Arjuna that comprises the Bhagavad-gita took place 5,000 years ago, just before the start of the battle of Kurukshetra, when the Pandava prince, Arjuna, was filled with doubt and confusion as on the opposing side are his relatives, beloved friends, and revered teachers. He turns to Lord Krishna, who was acting as his charioteer, for guidance, asking Krishna “please instruct me”. Responding to Arjuna's dilemma, Krishna explains to Arjuna his actual duty, giving Arjuna all manner of spiritual and practical advice. Krishna explains the eternal nature of the self, the difference between the atma (the self) and our material body, our relationship with the Supreme, karma, the purpose and goal of yoga, how our activities affect our consciousness, and ultimately, how to attain the perfection of life, pure love for the Supreme Soul.
Krishna, the Supreme Soul, has given us the perfect instruction of Bhagavad-gita to guide everyone on the path to self-realization, real happiness, and deep understanding of the Absolute Truth. As we face our own challenges and tribulations, large and small, the eternal truths spoken directly by Krishna apply today as much as they did 5000 years ago.
The Bhagavad-gita has inspired some of the world's greatest thinkers:
“When doubts haunt me, when disappointments stare me in the face, and I see not one ray of hope on the horizon, I turn to Bhagavad-gita and find a verse to comfort me; and I immediately begin to smile in the midst of overwhelming sorrow. My life has been full of external tragedies and if they have not left any visible or invisible effect on me, I owe it to the teaching of the Bhagavad-gita.”
"When I read the Bhagavad-gita and reflect about how God created this universe everything else seems so superfluous."
"The Bhagavad-gita has a profound influence on the spirit of mankind by its devotion to God which is manifested by actions."
Dr. Albert Schweizer
"In the morning I bathe my intellect in the stupendous and cosmogonal philosophy of the Bhagavad-gita, in comparison with which our modern world and its literature seems puny and trivial."
Henry David Thoreau
"The marvel of the Bhagavad-gita is its truly beautiful revelation of life's wisdom which enables philosophy to blossom into religion."
"On perusal of the first chapter of Bhagavad-gita one may think that they are advised to engage in warfare. When the second chapter has been read it can be clearly understood that knowledge and the soul is the ultimate goal to be attained. On studying the third chapter it is apparent that acts of righteousness are also of high priority. If we continue and patiently take the time to complete the Bhagavad-gita and try to ascertain the truth of its closing chapter we can see that the ultimate conclusion is to relinquish all the conceptualized ideas of religion which we possess and fully surrender directly unto the Supreme Lord."
Srila Bhaktivendanta Swami Prabhupada