Having thus spoken on the field of battle, Arjuna sat down on the chariot-seat, dropping his bow and arrows, with mind afflicted by sorrow

The first chapter culminates in physical action: upāviśat (sat down) — the posture of one who abandons. The rathopastha (seat/depth of the chariot) is where the warrior stands to shoot; to sit is to surrender.

Visṛjya (having released, abandoned) the cāpa (bow) sa-śaram (with arrow) — the abandonment of the instrument of his dharma. The bow is not respectfully put away; it is dropped.

The mental state is described with clinical precision: śoka-saṃvigna-mānasaḥ — mind (mānasa) agitated/violated (saṃvigna) by śoka (grief, lament, dark sorrow). It is not fear or anger; it is pure viṣāda (despair), the condition that defines this first chapter: Arjuna Viṣāda Yoga.

The warrior is broken. The teaching may begin.