We've written previously about the notion of art's immediate effect on the viewer (or listener) as one that precedes intellectual apprehension — we "feel" it before we can describe it.
Now there is a growing scientific consensus that this precognitive response is a real one, triggered by the release of so-called "feel-good" chemicals in the brain like dopamine – not unlike the feelings one has towards a loved one.
That's not to say that Art as a category of human endeavor is not able to accommodate other ways of apprehending, for example the more intellectual understanding required of a conceptual artwork. But it's probably not a stretch to suggest that the genesis of art was the desire to express oneself in a different way.
I found I could say things with color and shape that I couldn't say any other way – things I had no words for.
Georgia O'Keefe