"The big eyes and lips said: I'm young and vulnerable. I can't hurt you, and you want to protect me. And the rest said: I'm healthy, I won't make you sick. And no matter how you felt about a pretty, there was a part of you that thought: If we had kids, they'd be healthy too. I want this pretty person . . ." Scott Westerfeld, "Uglies"
Every time you look at a new face you subconsciously analyze all their features in one glance and classify them into one of three broad groups: pretty, ugly, or in-between. And most often we find ourselves in the third group. Why is it that we do this? It is human nature to strive for excellence, beauty, perfection. And no matter how much they deny this, no matter how much a person says that they only look on the inside, not the outside and all those other cliche terms, every single one of us has that little part of your brain that says, "He/She's pretty, I wish I could look like that person." Or "He/She's so ugly." Sorry to break it to you, folks, but we're all human being and there's no arguing with that.
So what do you see when you see a pretty person? Well, usually we look for the full lips, the big doe eyes, the pristine clear skin. We look for perfect symmetry, and a healthy figure. The Greeks believed that there was a ratio for beauty called Phi. Phi is 1.618 to 1. It actually appears in places all over the body of beautiful people such as the distance from the feet to the belly button and then the belly button to the head, or the ratio between the height and width of the head. Phi can be found in nature also. Although I'm not sure that beauty has all to do with math, I know that it plays a role in the way things are laid out and the way we see them.