नैनं छिन्दन्ति शस्त्राणि नैनं दहति पावकः।
न चैनं क्लेदयन्त्यापो न शोषयति मारुतः।।2.23।।
Weapons do not cut It, fire does not burn It, water does not moisten It, and air does not dry It.
A question was raised in the previous verse as to why does this embodied remain unchanged? The answer is provided in this shloka.
The subject of the discussion, embodied, the atman, cannot be cut by weapons or burnt by fire. Nor this embodied can be moistened by water or dried by air. This is because of the singular reason of the partlessness of atman. The embodied does not have parts. Only a thing with parts can be cut by weapons or burnt or moistened or dried.
Since this embodied is so, (in next shloka)
So the singular reasons of immutability of atman is explained as partlessness thereof.