Short answers, pulled from the story.
The Bhagavad Gita is a Hindu scripture, often called the Gita, likely composed in the second or first century BCE. It forms part of the epic Mahabharata and is set as a dialogue between the Pandava prince Arjuna and his charioteer Krishna at the onset of the Kurukshetra War.
In the Indian tradition the Bhagavad Gita is attributed to the sage Veda Vyasa, but it is historiographically regarded as a composite work by multiple authors. The Indologist Arthur Basham states there were three or more authors or compilers, and Alexus McLeod calls it impossible to link the Gita to a single author.
The Bhagavad Gita contains 18 chapters and 700 verses, structured mainly in the Anushthubh chanda meter for a total of 1,400 lines. Adi Shankara, in his eighth-century commentary, established 700 verses as the standard benchmark for the critical edition.
The Bhagavad Gita teaches three forms of spiritual discipline: jnana, the path of knowledge; bhakti, the path of loving devotion to Krishna; and karma, the path of selfless action. According to Upadhyaya, the Gita holds that none of these paths is intrinsically superior or inferior, and they converge toward the same goal.
In the Bhagavad Gita dharma fundamentally means that which is right or just, and contextually it covers duty, law, class, social norms, ritual, and the cosmos itself. Krishna asks Arjuna to follow his sva-dharma as a member of the kshatriya warrior varna, urging him to fight rather than abandon the battlefield.
In chapter eleven of the Bhagavad Gita, Krishna displays his universal form, the Vishvarupa, after giving Arjuna a heavenly eye to see it. Arjuna beholds a form bright as a thousand suns with no beginning, middle, or end, and a part of a verse from this chapter was recited by J. Robert Oppenheimer in a 1965 television documentary about the atomic bomb.