Srimad BhagavadGita

If Arjuna might say that, 'I know that souls are eternal and that only separation of the body from the soul happens when one is killed in a war. These bodies are the medium for experiencing beautiful pleasures in life. Then isn't it justified for me to experience grief over separation from such bodies when they are destroyed'. Kṛṣṇa presents this śloka as an answer to Arjuna. Kṛṣṇa says, "Just as a person casts off worn out  garments and puts on another new set, similarly the soul casts off bodies with which bondage (experience of fruits of karmas) is over and acquires other new bodies."

naraḥ yathā  jīrṇāni vāsāṃsi vihāya aparāṇi navāni gṛhṇāti (Just like a person casts off worn out garments and wears new ones)   

jīrṇāni vāsāṃsi (worn out garments) Since they are torn they are worth removing. One does not

experience grief while casting them off.   

navāni vāsāṃsi (another new set of garments) Since they are new, they are beautiful and hence worth

accepting. While accepting them, one experiences a lot of joy.

tathā dehī jīrṇāni śarīrāṇi vihāya anyāni navāni saṃyāti (Similar to the worldly example given, the embodied jīva too casts off his bodies with which bondage is over and acquires other new bodies)    

dehī (soul inside the deha) Dehī is one who goes from one body to another with ease.   

śarīrāṇi (bodies)The definition of the word śarīram is śīryate iti śarīraṃ (as it undergoes decay it is called

śarīra) Since perishing is śarīra's natural tendency, there is no need to grieve while casting it off.

jīrṇāni śarīrāṇi (worn out bodies) Moreover, since the bodies of Bhīṣma and others are old and worn out,

bondage with them is almost over and they will anyways perish very soon. While their bodies exist in this

worn out state, more misery is caused by them than comfort. 

anyāni navāni (other new bodies) 'O Arjuna!, Just as old, torn clothes are cast off and new clothes are

worn, when the old bodies with which bondage is over are cast off and other new bodies much more

attractive than them are taken up, one must feel happy and must not grieve like you. When you grieve over

the imperishable soul assuming it to be perishable, it is a flaw. Instead of becoming happy that a new

attractive body is going to be acquired by the soul, grieving over it is indeed a big flaw.

Q: Arjuna may raise a concern, 'It is not certain that when one body is given up and a new body is

acquired, the new body will be more attractive than the earlier body. One in an emperor's body may acquire

a new body suitable for the experience of hell on account of his karmas or may acquire moving/ stationery

bodies suitable for experiencing results of bad karmas or may not acquire a body at all just like at the time

of deluge. Hence, while leaving the body, it is not wrong for a person to fear about the kind of sinful body he

may acquire. Moreover, just the fact that it is a new body does not guarantee that it will give happiness and

comfort. What happiness lies in leaving the king's palace and moving into a new jail? Moreover, the act of

casting off torn clothes and wearing new ones is visible to our eyes but after losing this human body the act

of acquiring a new, more attractive body is not visible by us. Hence, it is justified for me to grieve over the

perishing of the body.

A: Kṛṣṇa's reply to Arjuna would be that, 'O Arjuna! You are going to separate their bodies from their souls

in a dharma yuddha (war fought by righteous means for a righteous cause). Our śāstras say that the warrior

who leaves his body in such a war attains vīra swarga (heaven). Hence it is certain that Bhīṣma and others

will acquire devata (celestial) bodies more attractive than the present ones. You should only be happy about

it and not grieve.