Contrast of light and dark is what gives form to every thing we see. Low contrast makes form fuzzy and unclear.
Finding form in light and darkness, we can create drama in an image.
Sometimes we are seduced by content, a topic or instance we see, and we create photos that have some interesting content. An example is a photo of our cute pet cat or dog and how they seem to be ‘smiling.’
It is when we see the light and dark values of a potential image when we finally begin to photograph the light.
Content can be utterly irrelevant. Say, a woman barbecuing on a grill.
Maybe the story of an image through content is ordinary, even mundane. But with attention to the way the frame portrays light and shadow, the image can transcend the content and become a record of light.