Using a reflective surface, you can 'guide' that excellent light source, the sun, onto your subject's face and get a pleasing look; and, in doing so, directing the light to the face creates what we in the field call a catch light so the eyes don't look like dark circles of blackness; like the darkness of your exes heart, but I digress, casting a reflected light source on to your subject always creates a pleasing look as well as a catchlight in their eyes.