Ahhh, I love this question. It's one of those things that puzzles me to no end, but I'm gonna take my best shot. I would have to say that one's concept of beauty comes from an endless combination of evaluations that our categorizing minds create. It is impossible to approach things objectively because our minds compare and categorize everything we experience whether we realize it or not. As someone said before, things may be beautiful in comparison to something else, but would we consider said thing beautiful if it were all we ever saw? In addition, everyone's idea of beauty is different. Granted, you could probably go out on a limb and say that there are some things that could be considered "universally beautiful," but it is extremely doubtful there there are two people on the planet who have the exact same idea of beauty. I tend to feel that the concept of beauty is one of nature's many paradoxes, kind of like personality, no one can explain where it comes from and everyones is different.