Bhagavad Gita Chapter 2, Verse 13

देहिनोऽस्मिन्यथा देहे कौमारं यौवनं जरा | तथा देहान्तरप्राप्तिर्धीरस्तत्र न मुह्यति ||

dehino 'smin yathā dehe kaumāraṁ yauvanaṁ jarā tathā dehāntara-prāptir dhīras tatra na muhyati

Just as the embodied soul continuously passes through childhood, youth, and old age in this body, so it passes into another body at death. The wise are not bewildered by this.

Arjuna is paralyzed by grief over fighting his family. Krishna responds with a profound analogy: just as the soul moves from childhood to youth to old age without dying, it moves to a new body at death. The key term 'dhīraḥ' (the wise/steady) captures those who aren't disturbed by these transitions. This isn't abstract philosophy—Krishna points to Arjuna's own experience. You've already 'died' to childhood and youth, yet you remain. Death is simply another transition, not annihilation but transformation.