"Nature" is what we see --
The Hill -- the Afternoon --
Squirrel -- Eclipse -- the Bumble bee --
Nay -- Nature is Heaven --
Nature is what we hear --
The Bobolink -- the Sea --
Thunder -- the Cricket --
Nay -- Nature is Harmony --
Nature is what we know --
Yet have no art to say --
So impotent Our Wisdom is
To her Simplicity.

She is saying that we should respect nature and preserve it.  We sin and do wrongs, but nature is perfect and does no wrong to anyone.