In "Nature," in what ways does Ralph Waldo Emerson show idealism in the work?

Emerson's
treatment of idealism in the essay "" is complex and ambivalent. For an example of
this complexity and ambivalence, we need look only to Emerson's understanding of the commonplace
meaning of "nature" relative to that of "art":

Nature, in the common sense, refers to essences unchanged by man; space, the
air, the river, the leaf. Art is applied to the mixture of his will with the same things, as in
a house, a canal, a statue, a picture.

Here,
nature appears to exist independently of the human mind. Nature is not the product of human
thought, and it may be beheld "unchanged" by the vicissitudes of human thought. And
yet, Emerson does not refer to nature as the physical world in the sense of the
chemically-composed, material (and or gaseous or liquid) substances out of which
"nature" in the physical sense is made. Notably, Emerson refers to
"essences" instead.

The problem with this is that
"essence" is nothing if not a concepta product of the human mind. Thus, to say
that...