देहिनोऽस्मिन्यथा देहे कौमारं यौवनं जरा । तथा देहान्तरप्राप्तिर्धीरस्तत्र न मुह्यति ॥
Transliteration
dehino 'smin yatha dehe kaumaram yauvanam jara tatha dehantara-praptir dhiras tatra na muhyati
Translation
As our body continuously passes from childhood to youth to old age, the soul similarly passes into another body after death. Wise men do not get bemused by such a change.
Purport
After explaining the continuity of life(Sh#12), Bhagvan Shri Krishna explained Arjuna, the secret of birth and death. Merciful Supreme Lord explained that birth and death is nothing but a physical change. Physical change is a continuous phenomenon which takes place in every physical substance all the time. Even the very body by which human identify himself is not same. It changes from childhood to adulthood to old age. In same fashion soul changes from one body to other, called as birth and death.