The blind king Dhritarashtra asks Sanjaya, who has the ability to see all, to tell him about the battle between his family and the Pandavas. The Pandavas include Arjuna and his brothers, who have come to take back the kingdom from Dhritarashtra, who means to bequeath it to his son Duryodhana, even though the crown rightfully belongs to Arjuna's brother Yudhishthira.
Prince Duroydhana, considered the nemesis for our protagonist Arjuna, approaches his teacher Drona, and lists out the key members of each side. He notes that his own army is unlimited, while the Pandavas is small. Each side blows their divine conchs, signaling the war is about to begin. Arjuna asks Krishna, who has taken the form of his charioteer, to drive them into the battle.
But as the chariot moves, Arjuna sees in the two armies the equal presence of his family, for Duryodhana, despite being his enemy, is also his cousin, and thus both sides are littered with "fathers, grandfathers, teachers, brothers, uncles, grandsons, in-laws and friends." Arjuna is overcome with despair and tells Krishna that he has no desire to fight if it means killing his kin. He has no need for a kingdom if it means destroying a family. He casts away his bow and arrows and sits in the chariot in the middle of the battlefield.
Krishna tells Arjuna to arise with a brave heart and push forward to destroy the enemy. When Arjuna questions how he can support such sin, Krishna says there is no such thing as the killer and the killed, that the body is merely flesh -- and that at the time of death he attains another body. These limits of the superficial body should not stop someone from doing what he must do, namely defeating evil and restoring the power of good.
The true master, says Krishna, realizes that reality lies in the eternal; such people are not affected by the temporary changes that come with the senses. Instead, as a warrior, he must follow his dharma, or duty, where nothing is higher than the war against evil. If he shirks from this battle, however, then Arjuna will incur sin, violating his dharma and his honor.
In Krishna's eyes, death means the attainment of heaven, and victory the enjoyment of earth, so there will be no pain in fighting. Krishna also extols the notion of yoga -- or skill in action -- as a path towards finding resoluteness, focus. He encourages Arjuna to not see the results of action, but rather focus on the work itself -- as a man within himself, without selfish attachments, alike in success and defeat.
Krishna tells Arjuna that the definition of a wise man is one who is unconcerned with whether things are "good or bad," but rather abandon attachments to the fruits of labor, allowing them to attain a state beyond evil. When a man is unmoved by the confusion of ideas, and is united simply in the peace of action without thoughts of results, he can attain perfect yoga. Arjuna asks what a man who has achieved perfect yoga acts like -- how he sits, how he moves, how he can be recognized.
Krishna says this kind of man is not agitated by negative emotions -- lust, fear, anger. They are naturally meditative, and do not respond to good fortune or bad fortune. They have no attachment to the material, and live not in the senses, but in the self. They are free from ego -- the 'I, me, mine' which cause pain.
The opening of the Bhagavad Gita can be intimidating because of the sheer number of names and terms that come out of Sanjaya and Dhritarashtra that will be unfamiliar to those not well-versed in Hinduism. But the new reader should see the first chapter merely as historical context for what is to follow, which is essentially a two-person conversation about philosophy and yogic principles, as opposed to a treatise of battle, which the first chapter seems to lay out. Indeed, all we really need to understand in this first chapter is the background of the conflict -- that Arjuna must avenge Dhritarashtra's passing of the kingdom to his own son, rather than to Arjuna's brother Yudhishthira, the rightful king -- and the nature of Arjuna's inner turmoil over the fact he must kill his own family members.
Arjuna, then, finds himself in a similar position as Hamlet -- having to fight his uncle for the control of a crown that he doesn't necessarily want. Krishna, as the divine voice of yoga, dharma, and karma, must not only convince Arjuna to fight, but to fight with the will to win -- to restore good, to restore balance, to fulfill his duty as a warrior. In the process of convincing him, Krishna will lay out essentially a philosophy for living, and the basic tenets of Hinduism.
A few key terms must be understood in order to move forward. Dharma is the Hindu concept of 'duty.' In each life, we are reborn in accordance with our karma - which is simply the cumulative effect of our actions. Hinduism sees our life as a series of actions which have consequences - everything we do is part of a web of consequences which affects others, and thus every action has a 'reaction.' Our life is about living out the effects of these reactions, and we are reborn having to continually live out the debts that come with negative actions, until we end the cycle of birth and death by bearing out our karma. Dharma, then, or 'duty,' is simply that which we must do in each life in order to restore the rightful balance of karma.
Accordingly, then, Krishna tells Arjuna that his dharma in this life is to be a warrior and rightfully fight against Duryodhana for the kingdom so that he may restore good -- his karma requires this grand staging of good vs. evil to right the balance. It is not his duty to see myopically, to simply see the boundaries of life and death, but rather to live beyond results and in the larger cycle of samsara, or the karmic circle.
Arjuna asks Krishna what a man who is freed from mundane concerns is like, what a wise man does in life on a daily basis. It is a truly wonderful question, for it hits at why most laymen are afraid of pursuing a spiritual path -- namely the idea that they have to give up the world in order to find peace. Arjuna says that such a man lives in the world, but simply has no concern for results. He finds peace in the work, peace in the universe, because he has found himself. There is no such thing as good or bad, there is no such thing as life and death. There is what he sees and nothing more.