Our sweetest songs are those that tell us of saddest thoughts these words are attributed to?

Our sweetest songs are those that tell us of saddest thoughts these words are attributed to?

ہمارے سب سے پیارے گانے وہ ہیں جو ہمیں دکھ بھرے خیالات بتاتے ہیں یہ الفاظ کس سے منسوب ہیں؟
Explanation

Shelley's "Mont Blanc" is written in blank verse,

Which means unrhymed iambic pentameter.