Shapes in shadows
all visually isolated objects have a shape, often the shapes that
have the most graphic impact in an image are those that occur
less obviously from the congruence of intact elements. Perhaps
where an object and a shadow combine to create a more ambiguous
or abstract shape.
In this image from my Entropy series - As with a piece of music, you can see how the burnt tree shapes and shadows create a repetitive pattern that gives the image design a sense of repetition and rhythm. This visual rhythm is a key aspect of the images from this series, and often shadows are used to enhance the effect.