I brew for the love of science, math, and cooking.......... but the best beers I have made were the ones that were artistically inspired.... you know, the ones where you imagine what a beer tastes like, with total disregard for style, and then it actually turns out like you imagined it..... those are my favorities. The ones where I follow a formula or adjust someone else's recipe, those tend to not be quite as awesome.
So for me, it's the whole package that keeps me going. Science, math, and art.... The whole package.