The poem's writing will not be destroyed in any condition whereas the monuments might get destroyed by sluttish time, in war etc.
I hope the answer is right!!
1
Vasanth answered this
Pen is more powerful than time and sword indeed. The poet through his pen immortalized his friend by preserving the memory of his good deeds in the poem , 'Not Marbles, Nor the Gilded Monuments'; this memory of his friend's good deeds will be handed down from one generation to another till the end of times. Neither time, nor sword will be able to obliterate this memory. So in this sense, pen is mightier than time and sword.