Art is the surest proof of man's higher faculties because it's purpose is to express abstractions which reflects reality or reflect reality through abstractions. Concepts and ideas are windows to the inner dimension of a subject underneath an object , thus it's sole purpose is to reflect something abstract in a physical or tangible form of beauty making it intelligible to a subject from the point of view of another subject sharing it's interiority through an object. It is a reflection of man's inner dimensionality because it goes beyond "what is" to "who is" or "why is".
Imagination, creativity, and the anlysis of what is imagined and created solely belongs to beings with the capacity for reason. Art being the progeny of the imaginative and creative process is a mirror to this capacity. This mirror reflects our interiority and in my belief, this interior dimension, that which elevates from being objects merely on the vegetive or sensitive levels to subjects on the intellective level is proof of man's capacity for something way beyond what is merely mundane.