From women’s eyes this doctrine I derive:
They sparkle still the right Promethean fire;
They are the books, the arts, the academes,
That show, contain, and nourish all the world. -- Loves Labour's Lost, Act IV, Scene III
My Take - The girl with the sparkle or the fire in her eyes is the one that always caught my attention. A woman that gets and holds your eyes when you speak with her is confident and ready to be a partner in whatever way she chooses.