Bhagavad-gītā As It Is 2.13
dehino 'smin yathā dehe kaumāraḿ yauvanaḿ jarā tathā dehāntara-prāptir dhīras tatra na muhyati
As the embodied soul continuously passes, in this body, from boyhood to youth to old age, the soul similarly passes into another body at death. A sober person is not bewildered by such a change.
PURPORT
Since every living entity is an individual soul, each is changing his body every moment, manifesting sometimes as a child, sometimes as a youth, and sometimes as an old man. Yet the same spirit soul is there and does not undergo any change. This individual soul finally changes the body at death and transmigrates to another body; and since it is sure to have another body in the next birth — either material or spiritual — there was no cause for