Bhagavad Gita 2.13 · BG 2.13
Chapter 2Verse 13
Sankhya Yoga
देहिनोऽस्मिन्यथा देहे कौमारं यौवनं जरा। तथा देहान्तरप्राप्तिर्धीरस्तत्र न मुह्यति॥
dehino 'smin yathā dehe kaumāraṁ yauvanaṁ jarā, tathā dehāntara-prāptir dhīras tatra na muhyati
Translation
Just as the embodied self passes, within this body, through childhood, youth, and old age, so too it passes into another body at death. The wise are not troubled by this.
You've already changed bodies once, from child to now. Death is just the next change.
What does this mean?
Growing older is already a series of small departures. You aren't the child you were, and you're not upset about that. This verse asks you to hold the biggest departure of all with that same steadiness.
In simple words
Krishna points out that you've already lived through big changes of body, from child to teenager to adult, without being destroyed by any of them. Death, he says, is the next change of that kind. The steady person doesn't panic about it.
The deeper idea
The argument works by analogy. You accept that the child you were is gone and you aren't in mourning about it, because you experience yourself as continuous through those changes. The verse asks you to extend that same sense of continuity across the largest change. 'The wise are not troubled' doesn't mean they feel nothing. It means they've stopped treating each transformation of the body as the end of the self that moves through them.
How it applies to life
Look at an old photo of yourself at seven. That body is gone, most of those cells long since replaced, and yet there's an unbroken thread of you connecting then to now. Aging is already a slow series of these departures, and you've made peace with most of them without noticing. This verse asks you to bring that same unpanicked steadiness to thinking about the last one.