When you shimmer you shine, although sometimes quite weakly.
A shimmer is small and sometimes weak, and in danger of going out, but it's there all the same and often beautiful. You know how silk catches the light and shines in lovely ways? That's a shimmer. How about when you feel like it's the end of the world but there's a little piece of you that believes things are going to get better? That's a shimmer of hope. Or when you open a door to a dark room and the light from the hall falls into the darkness? That's a shimmer of light.