अविनाशि तु तद्विद्धि येन सर्वमिदं ततम्।
विनाशमव्ययस्यास्य न कश्िचत् कर्तुमर्हति।।2.17।।
It should be understood that the soul is indestructible and is the principle by which the physical body is permeated. The insentient body is completely distinct from the sentient soul. By reason of its pervasive nature the soul is very subtle, in fact so exceedingly subtle is the soul that it is verily incapable of being destroyed being subatomic in essence. There is no thing which is of different or of a dissimilar nature from it which in any way is capable of destroying the soul. For whatever there is existing is pervaded by the soul as well and being pervaded by the soul itself verifies its less gross and most subtle position of all being subatomic. Such things as weapons, water, fire, air, cold etc. can not influence or be the agents of destruction for the imperishable soul, being all pervaded by it. The rationale of a hammer striking an object and disintegrating it is now given. When a hammer strikes an object with excessive force an extreme vibration produces a molecular disruption which causes the destruction of the object. But in the case of the soul there is no facility for destruction as when light penetrates a glass jar is not destroyed when the glass is destroyed; similarly the soul is like unto this in relation to the body. Thus it can be understood the imperishable nature of the soul. Now the next verse explains that being perishable is the very nature of the physical body.