I dont have the answer, but a limited government is basically a government with limited authority over the citizens; for example, freedom of speech, press, and religion. the government cant control that. they cant control who an individual votes for in a democracy either. thats a limited but fair government.
Metaphors and similes are used to add depth and meaning to the poem, so it looks normal on the surface but when you re-read it you uncover a deeper meaning :)