The ancient Greeks thought that proportion was the key to beauty.The Greeks believed that they had discovered the mathematical formula that represented perfect beauty.According to this formula,for example,the ideal face was two-thirds as wide as it was high. Modern research has proven that the basic concept of the Greeks'formula,if not the formula itself,was correct:Beauty does seem to relate to proportion and balance. When related to beauty,these qualities are called symmetry.A perfectly symmetrical face would have a left side that is identical to its right side.