I don't think I have much to add to what's been said, except that--talking about Nietszche--, Heidegger once wrote an essay called "The origin of the work of art". Not only does it explain what he thinks art is, and how it uses the artist rather than the other way around, he also questions and tries to understand the "is" of this last sentence. Apparently, an artist's (should he choose to call himself that) art is much more interesting when he's read non-cartesian philosophy (that is, Plato, Kant and Heidegger). The only thing I think I can suggest is that philosophy thinks being (the verb+noun). Art, on the other equally-valuable hand, feels it.
Not that it is respectively so in this case, but Tarkovsky suggested symbolism as a complex formula that can be intellectually split apart (first thought, then felt) while metaphors, however, are first to be felt and then thought. In this sense, philosophy and art are both a combination of each other and need each other to bear meaning about themselves, but philosophy analogically leans towards intellectualism whilst art does to emotion. Here's a quote from an interview of his:
"We can express our feelings regarding the world around us either by poetic or by descriptive means. I prefer to express myself metaphorically. Let me stress: metaphorically, not symbolically. A symbol contains within itself a definite meaning, certain intellectual formula, while metaphor is an image. An image possessing the same distinguishing features as the world it represents. An image — as opposed to a symbol — is indefinite in meaning. One cannot speak of the infinite world by applying tools that are definite and finite. We can analyse the formula that constitutes a symbol, while metaphor is a being-within-itself, it's a monomial. It falls apart at any attempt of touching it."
(
http://people.ucalgary.ca/~tstronds/nostalghia.com/TheTopics/Symbols.html)
What is more important, it would seem as though art finds us and invades our vision; art could be a landscape, or the stars, or Bach's music. But once we're moved by these things, we cannot escape them, and they will force themselves upon us every time we create something we call artistic. Sorry for dragging the subject away from your piece, Helm. I very much digress all the time. Thanks for taking the time to read this.