(see Julian Young, Nietzsche's Philosophy of Art, 10ff)
Schopenhauer's aesthetics starts from the conviction that there is a special kind of consciousness or perception which is uniquely aesthetic. Any real work of art has to come out of this consciousness. You might call it genius, following the earlier romantics, as long as that doesn't suggest that only good art comes from genius, and the rest comes from ordinary consciousness. In fact, all art must come from this consciousness, and bad art isn't really art at all. So, this consciousness is a rare and transcendent ability above our ordinary way of perceiving the world.
Ordinarily we identify ourselves with empirical individuals, an object among other objects in the spatial and temporal world. We can only locate other objects if we relate to them on their terms, spatio-temporally, and these objects are related to us as if we are the centre of the world. For Schopenhauer, our essence is to will, and we view objects around us in relation to that will, either as threats to our well-being or as satisfiers of our desires. This means, though, that we manipulate our sensory data in the interests of that will. So, if I am in a hurry to get somewhere, the bridge I travel over is nothing more than a "dash intersecting with a stroke".
This ordinary consciousness leaves us in suffering and anxiety. The reason is that there is a disjunction between the will and the world. The world is hardly ever the way we want it to be. And even when it is, we suffer boredom, a pressure of the will that lacks any object to express itself. Everyday life is a mixture of pain, anxiety, and boredom.
So ordinary consciousness is not much fun. We are basically egocentric, we manipulate the perceptual content of the world by our will. Aesthetic consciousness is different – these features are not there. How does this happen? When we "lose ourselves in the object of perception so that we are no longer able to separate the perceiver from the perception but the two have become one since the entire consciousness is filled and occupied by a single image of perception. (WR I, 118-119). We cease to be aware of ourselves as spatio-temporal objects amidst other s-t objects, and so cease to view individual objects as objects of our will. We become (like for Kant) disinterested. The subjectivity of ordinary consciousness disappears – perception becomes "objective" – and pain disappears. If my consciousness is absorbed in the object of perception, I can't be aware of a disjunction between will and object, nor can the will be objectless. This is aesthetic pleasure. Example: if you are completely absorbed in an aesthetic object, either in creating or in experiencing, you aren't thinking of you as creating it or viewing it, but you enter into its world. Music can "carry you away", and you become "ecstatic", out of yourself. But that "out of" does not suggest that you are in another self, but in no-self. The aesthetic state is a glimpse of the permanent solution to the problem of pain.
So, the subject, the person, is transformed in aesthetic consciousness. But so is the object of consciousness. We cease being aware of ourselves in the here and now, and because of this we are also unaware of objects in this world as well. We cease perceiving the world as composed of individuals. In fact, what we perceive are Platonic Forms, which are not objects at all. But it should be noted that we are not perceiving the universal apple (or whatever) or the Idea of apple, but the apple as Idea, or what persists in the particular apple. What's the difference?
It is the relationship between art and nature. For Plato, art obscures nature. For Aristotle, art repeats nature. For Schopenhauer, art eliminates (or de-emphasizes) nature, or at least the parts of nature that are not to its purpose. So, even though Schopenhauer uses Platonic terminology, he gives us a kind of inversion of Plato. Plato thinks that philosophy is better than art because philosophy gives us real knowledge. Schopenhauer responds that in fact art gives us real knowledge, in that it gives us a consciousness that can access what is permanent, and it enables us to tell the difference between the ephemeral and the real.
Art must be rooted in natural representation, Schopenhauer thought. He eschewed artificial work. Only the representational work is able to remain "young and strong". Schopenhauer argued for representation not because it was representation of the phenomenal, but of the manifestations of will. The supreme form of representational art for Schopenhauer was tragedy. It makes most evident the "conflict of the will with itself -- a conflict brought about by disunity and individuation." Will becomes visible in the suffering of humanity, and appears represented as chance, error, and "malice personified as fate." We particularly do not want art that arouses the passions or expresses emotion – that's desire, and is akin to pornography. But one must be careful here – it is individual emotion that is problematic for him. It is individual will that causes problems for us. We might have more general feelings, in the aesthetic moment, that do not simply add to pain and thus reduce the moment to ordinary consciousness. We may, for example, feel emotion in the presence of the sublime which does not come out of individual consciousness.
But there is an even greater art form, one that does not rely on representation/non-representation, or on the mediation of pre-existing forms. It is music, the greatest form. Music is in no way an image of ideas, but is a direct image of the will itself. It is the work of the genius. Music is completely independent of individuals. It is pure intuition, but it is not just abstraction of individuals, either.
This suggests that Schopenhauer, like Hegel, has a hierarchy of the arts. Architecture is the lowest art for him, since it has as its central concern the "dullest visibility" of the will, the play between gravity and material. At the other end of the hierarchy, as for Hegel, is poetry, since they reveal the metaphysical world most clearly.