The golden ratio is what I think you mean. Also known as the golden spiral, mean, rule, etc.
To sum it up it refers to the natural beauty of aesthetics that can be found in art, architecture, the human face, mathmatics, and a whole load of subjects.
I've always "interpreted" it as being the mathematical explanation for the natural beauty of aesthetics that can be found in art architecture, the human face, and a whole load of subjects...meslef.

do I have to look it up again?

I think Vintage Paw should do the Googling coz she's telling teh porkies.
