The Yoga of Knowledge

Krishna concludes his teaching on the Self with a radical expansion: the dehī (embodied consciousness) isn't just indestructible—it's universal. 'Dehe sarvasya' (in the body of all) means the same consciousness inhabits every being. Arjuna's consciousness and Bhishma's aren't separate entities but one awareness appearing as two, like the ocean appearing as many waves. This is Advaita (non-dualism): many bodies, one consciousness. Therefore—'tasmāt sarvāṇi bhūtāni na tvaṁ śocitum arhasi'—you shouldn't grieve for any being. Not because they don't matter, but because what they fundamentally are cannot be harmed. Bodies change; consciousness doesn't.