This really confuses me. Can someone help??
In "The Cloud" the word mantle means the clouds-

Answer:
if you mean the first line of the second paragraph, that is I throw my mantle over the moon, it basically means a cloak.
the line means "I cause a lunar eclipse by throwing my cloak on top of the moon"
the character is expressing itself as being powerful.
such a beautiful composition. hope it helps you.