नैनं छिन्दन्ति शस्त्राणि नैनं दहति पावकः।न चैनं क्लेदयन्त्यापो न शोषयति मारुतः॥
nainaṃ chindanti śastrāṇi nainaṃ dahati pāvakaḥna cainaṃ kledayantyāpo na śoṣayati mārutaḥ
Word by word
The verse says
Weapons do not cut it. Fire does not burn it. Water does not soak it. Wind does not dry it out.
In plain words
Four denials, one for each element.
This is not decoration. In the old physics these four are what destroys things. Krishna is going through the complete list of ways a thing can be ruined and marking each one not applicable.
And the first is a weapon. He begins with Arjuna's own trade.
Where you've felt this · in study
You run a small business, and one night you list every way it could fail - the whole list, done properly. None of them is the thing keeping you awake. The fear does not go anywhere. You simply find you can no longer say what it is afraid of.
Going deeper
The four items are the classical elements minus one, and the omission is interesting: earth is missing, and space is not mentioned.
What is listed are the four active destroyers. Cutting, burning, dissolving, desiccating - the ways matter is taken apart. Krishna runs the full inventory of destruction and finds nothing that applies.
The rhetorical structure matters too. He does not argue. He lists. This is closer to a chant than to a proof, and later tradition has used these verses exactly that way, recited at cremations for centuries.
That liturgical weight can obscure what the verse is doing here, which is narrower and more pointed. Arjuna holds a weapon. He has been imagining, in detail, what that weapon will do to his grandfather.
Krishna begins the list with śastrāṇi - weapons - because that is the specific object of Arjuna's horror. The verse looks universal and is in fact precisely aimed.