From The Vine:
For thousands of years the mouth has been considered the most sensual part of the face. And whether we know it or not, whether we'll admit to it or not, we women have relished in exploiting the mouth's powers by decorating and enhancing our lips. It'd be careless to view lipstick as merely seductive, however. Depending on the colour, and the shape of the lip line, lipstick is also a symbol of power, of sophistication, of rebellion, of courage, of optimism and more.