The ability to see light is a fundamental part of the art of photography. Obviously we see light in the simple physical sense, but that is only the beginning. A much more perceptive approach has to be developed.
When we look at a scene it is the dominant shapes and colours that are most readily retained by the brain. Subordinate detail, such as the illumination of particular features, is unimportant in the context of everyday life and hence easily overlooked.
The eye must therefore be trained to see the quality of light in an analytical manner. First, ask what initially attracted your attention to a subject and strive to incorporate this into your image. Then identify and evaluate the more subtle characteristics of light that make a scene special. They are essential ingredients for a successful image. Note the direction of the light and how it falls on your subject, and be aware of areas of shadow. Observe the light's harshness and colour, and remain sensitive to their implications in terms of mood.