Second episode/adhyaya – Sankhya yoga
dehino ‘smin yathā dehe
dehinaḥ—of the embodied; asmin—in this; yathā—as; dehe—in the body; kaumāram—boyhood; yauvanam—youth; jarā—old age; tathā—similarly; dehāntara—transference of the body; prāptiḥ—achievement; dhīraḥ—the sober; tatra—thereupon; na—never; muhyati—deluded.
Text Source – “http://prabhupadabooks.com/bg”
As the embodied undergoes kaumaram(boyhood), yauvanam(youth) and then jara(old age) in the body, similarly it undergoes dehantara(death and going to the next body). Dhirah(the knowledgable) is not deluded with such a transference.
Sri Krishna is explaining how we are always there, as we move from one body to another.
We were children, then teenagers, then adults and then we’ll become old. This change is happening to the body. But something in us is not changing. We still remember our childhood as though it happened few years back. We know it’s us who experienced everything in the past, though our body doesn’t look the same. This something which is unchanging(the embodied) thus moves on to the next body after death. So what we call death is probably us moving on to the next body, leaving our old body behind. So the knowledgable won’t lament on death, as it is only the body that dies.
But then what about the relationships? what about the people that were left behind? they need not reunite in the next life as well. Arjuna is perhaps lamenting at the loss of his relationship with his grandfather. So it’s the relationships and associations we lament.
May be from an older person’s perspective, leaving the old, frail body and moving onto a new, young body, is desirable.