The central theme of Chapter 1 (Arjuna Visada Yoga) is Arjuna’s intense moral dilemma and complete emotional collapse on the battlefield of Kurukshetra.
When Shri Krishna places the chariot between the two opposing armies at Arjuna's request, Arjuna looks across and realizes that victory requires slaughtering his own teachers, elders, cousins, and lifelong friends. Overwhelmed by grief, his limbs tremble, his mouth goes dry, his skin burns, and his famous bow (Gandiva) slips from his hand.
Arjuna argues that winning a kingdom at the cost of his family's blood is meaningless, as it destroys family traditions, leads to societal collapse, and brings grave sin. Unable to resolve this inner conflict between his duty as a warrior and his personal morality, Arjuna drops his weapons, sits down in the chariot overwhelmed with sorrow, and surrenders his resolve to fight.
This total breakdown serves as the crucial catalyst for the entire Gita: it demonstrates that physical power and human intellect fail in moments of existential crisis, setting the stage for divine wisdom to begin in Chapter 2.