Chapter 2, Verse 13
Part of 2: Sānkhya Yog — सांख्ययोगदेहिनोऽस्मिन्यथा 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 passes through childhood, youth, and old age in this body, so too does it pass into another body; the steadfast one does not grieve over this.
-- Just as there is no interruption in the passing of childhood into youth and youth into old age in this body, so also there is no interruption by death in the continuity of the ego. The Self is not dead at the termination of the stage, viz., childhood. It is certainly not born again at the beginning of the second stage, viz., youth. Just as the Self passes unchanged from childhood to youth and from yourth to old age, so also the Self passes unchanged from one body into,another. Therefore, the wise man is not at all distressed about it.