If you see the contents of Mahabharatha, in addition to the main story, we can find innumerable places where philosophical and spiritual knowledge has been placed. Take for example: the Yaksha prashna, Viduraneeti, Shrikrishna Sandhaana, Bhishma’s teachings to Yudhisthira, the entire Vanaparva where the Pandavas interact with various sages in the forest, etc etc. And of course, the Bhagavad Geeta.
Coming to your question, what I feel might have actually happened is this: sometime before the war actually began, Arjuna developed cold feet when he realised that he is going to a war with his own relatives and brothers, and must have hesitated to fight. This apprehension of his was countered by the collective efforts of all the Pandava biggies, with the assistance of the great Krishna, who made Arjuna remember the imense amount of injustice meted out by the Kauravas onto them. Arjuna realized his blunder and decided to fight.
However, while narrating the story, Vedavyasa might have seen an opportunity to include some immense values and philosophies at this juncture. Look at the scenario: Arjuna is in the middle of battlefield, and is confused as to whether he should do his duties and fight, or be morally correct and not slay his relatives! With this confusion, he throws away his weapons and sits down. Krishna comes into rescue, and gives totally practical advices!
Sample this: “Do your duties, and leave the rest to the God! Do not expect anything in return; if you deserve it, you will get it! Do not procrastinate!”
(कर्मण्येवधिकरस्ते मा फलेषु कदाचन | मा कर्मफलहेतुर्भू मा ते संगोस्त्वकर्मणि ||)
Or this: “It is the body that dies, not the soul! Soul merely changes bodies, like a man changes his clothes!”
(वसांसि जीर्णानि यथा विहय नवानि गृण्हाति नरोपराणि | तथा शरीराणि विहाय जीर्णानि अन्यानि संयाति नवानि देही ||)
This, and many other practical advises!
Conflict in the mind of a person going into war is so relatable to any person, in some part of his or her life: being in conflict over performing his or her duties. This is the scenario when Krishna comes as a saviour and gives practical solutions. I feel that it is for this reason why the Bhagavad geetha has become so popular world-wide: the positioning and timing! This is another indication towards the genius of Vedavyasa!
it’s not you who chooses to read gita, perhaps its gita who chooses you to read it, in some or other point in time in life. its a magical book in this material world. and the god in this magical book is even greater magician. stopping time is a no big deal. i believe you agree.
Source . Quora