An Aesthetic Dream!
In order to assume the essence of Art, one must tread back to Plato's Republic, and reminisce on Plato's thought. He postulated that Art was an imitation of the Form's imitation.
Allow me to explain...
Plato believed that life was an imitation of the Form. The Form is the real part of life that man cannot see, because it is an abstract entity within a world of it's own. Therefore, when a painter creates a work of art, he is only copying an imitation, which we call life.
The graphic illustration below sums it up:
Nietzsche's Problem?
Friedrich Nietzsche held a perpetual hatred towards Plato and Socrates. Anything that came out of Plato's mouth made Nietzsche vomit! So, it's no surprise that Nietzsche's view on Art differed from Plato's.
Nietzsche at heart was an artist. He held Art to be on par with Nature. He quotes:
" Art is not merely an imitation of the reality of nature, but in truth a metaphysical supplement to the reality of nature, placed alongside thereof for its conquest."
Conclusion
Without a doubt, it is quite obvious that Art is an imitation of some kind. Whether that art is abstract, cubist, or postmodern, it will always be copying the immaterial thoughts gained from a material world.